This Book looks at physical feats for creatures of all shapes and sizes, with detailed computations of performance statistics. They're easier than computing a plane's top speed in Vehicles, but similar in concept.
The rules on jumping and throwing look bizarrely long, but they turn out to be unusually rich topics and find application in the oddest places.
RPGs go all out with the specifics of combat, but detail in other physical actions can be fun too. This is your Book if you want to replace duels with athletic competitions once in a while. Or imagine a game of unarmed athletes thrown into a dangerous world. Can they survive without Broadsword and Polearm, on wits and athletic skills alone? Ask that Orc with the 90 mph fastball rock embedded in his forehead.
Your Basic Speed (or Speed; GURPS uses both terms) is a measure of your innate quickness of movement. It's the base for both your Move and Dodge. It's an "intrinsic" score, unaffected by your size or your running efficiency, and can easily be the same for a human, an insect, and a dinosaur.
The calculation is (DX+HT)/4; other details are as per the BS.
GULLIVER's big change to movement rules is this: all forms of movement use the same rules for speed and performance. This isn't currently the case in GURPS, where running and flying Move, for example, come from Basic Speed, while swimming and climbing Move don't.
All forms of movement start with a Base Move and then modify it. You can juggle the order of these adjustments; the only important rule is that additions/subtractions to Base Move come before multiplications/divisions.
The components of mobility are:
The "adjustments" part looks intense, but most of those won't apply in a given situation.
Start with Basic Speed. Don't round yet.
Some players have suggested that Base Move or even Basic Speed should be computed with ST in the equation, at least for some forms of movement (such as sprinting), to account for the effects of power.
It sounds good, but doesn't work. Try (DX+ST)/4 as a base, and you'll get slow-motion squirrels and supersonic sauropods, when the effect you want is just the opposite. As always, power itself is meaningless; it's power vs mass to be moved that matters. Natural encumbrance rules take care of that.
Adjust for each of the following:
Skills that affect movement usually work in one of two ways:
Note: When skill adds to Base Move, such as in Running, an interesting option is to instead replace HT or DX in the Basic Speed equation with skill level. See notes in the Appendix.
Skill level and encumbrance: Skills like Swimming and Climbing are adjusted for encumbrance. That's fine for control roll purposes, but not for Move adjustment purposes encumbrance already takes care of the Move factor. When incorporating these skills into Move, use skill unadjusted for encumbrance.
Instead of the GURPS method of adjusting Move for encumbrance, GULLIVER multiplies Base Move by Move Modifier (see Book 2).
An important point from Book 2 for swimmers or fliers: Encumbrance from positive or negative weight affects you only when you fight it (to move on a level, or climb/sink in the opposite direction). If you let yourself freely float or sink with the weight, you can recalculate your encumbrance based on zero weight.
GULLIVER rules that if you're poorly adapted to move in an Environment an aquatic creature on land, for instance you face a flat x1/10 multiplier to Move (though skill can usually improve things). Book 3 calls this a built-in five levels of Reduced Move, though the name isn't important.
Flying is an exception: if you're not adapted for flight, you don't fly at all. Finally, Book 3 introduces disadvantages like No Climbing and No Jump, which also totally remove a form of movement.
With equal stats, size, skills, and encumbrance, one creature may still be faster than another, thanks to design: stronger or more legs, improved wing design, whatever. This is catchall "efficiency" of movement. (For ease of discussion, "enhancements" here covers any modification, including mobility restrictions.) You don't need biomechanical calculations to handle these just Enhanced or Reduced Move, Super Running, and so on.
Reduced Move: GULLIVER uses fractional Move multipliers for the Reduced Move trait (see Book 3), not subtractions: x2/3, x1/2, x1/3, x1/5, and x1/10, respectively, for 1 to 5 levels of the disadvantage. If you prefer GURPS' subtraction method, go for it but make the subtractions before any multiplications.
Multiply Move by Linear Scale. See Book 1 for details and alternatives. Together, size and natural encumbrance adjustments realistically simulate creature speeds.
If you don't use natural encumbrance adjustments from Book 2, Linear Scale overstates the effects of size on Move. To fix this, adjust Move as if you had only half your levels of Size, rounded favorably. For example, if you're Size -4 or -5, multiply Move as if you were only Size -2, or Linear Scale x1/2.
This is the catchall adjustment that establishes default flying speed as faster than running speed, etc.
What's left after the above is your final Move. Jot it down, fractions and all; those fractions are meaningful for long-term movement, or for restating Move in terms of different-sized hexes. For short-term (per turn) movement, round the number down.
Your computed Move is just a game stat; you can move more slowly or quickly than that.
Notes on energy use fatigue are included below, but see Book 6 for more on fatigue, including the effects of encumbrance, heat, and other factors.
Step doesn't mean a literal step; humans, snakes, and hummingbirds all have a "Step" distance for game purposes. It's the amount you can Move in a turn while still taking an action like an attack. For any form of movement:
Round as appropriate for the hex size in use.
The Table below summarizes other rates of movement, with suggested fatigue costs. (The cost for brisk and very brisk movement is new; the cost for fast movement differs from the GURPS suggestion for fatigue from running. See notes in Book 6.)
The only way you can go faster than a sprint is to use Extra Effort.
Move and actions: GURPS assumes you can defend normally while running, but cannot attack. (An exception is the All-Out Charge from CII p. 56.)
The game doesn't say anything about sprinting and actions. Consider sprinting "All-Out Move", combining two Move actions (with the special effect of adding a little extra Move, not doubling it). That would leave no room for attacks or active defenses when sprinting.
Move is greater than...
type of Move
very brisk ("fast jogging")
x1 + Sprint bonus
x1 + Sprint bonus
Extra Effort sprinting
Just staying aloft is tiring for a hovering bird, or a swimmer burdened with weight (see notes in Book 2). These travelers pay two fatigue costs: one to fight gravity, and one to move forward.
To fight gravity, apply 1 point of fatigue every 5 minutes, adjusted for Move Modifier, but with Move Modifier based on WSR only. This is the cost of keeping from falling, before moving anywhere. Of course, a swimmer or flier who lets himself fall freely with gravity i.e., a glider doesn't pay this cost.
Then pay the above costs for forward movement.
When you need to hang a sharp turn, jump an iffy chasm, or pull ahead in a foot race, make a control roll against the appropriate skill or attribute. Modifiers for encumbrance are usually appropriate.
The number of appendages you have to assist in making a maneuver feet on the ground, feet and hands on a climbing surface, fins in the water, etc. affects control rolls. Unless rules state otherwise, use this master rule for all situations:
A common application is number of legs and balance rolls. A running dog receives a +2 on balance or other control rolls for four legs on the ground; a dog balancing on its hind legs receives +0 for two legs (and additional penalties for poor balance; dogs aren't made to walk upright). See Balance.
These rules are optional, as in GURPS. It's interesting to see how nimbly your flier or swimmer can zig and zag, but drop the rules if they slow down play.
For any form of movement, use the turning radius rules from BS p. 139: one 60° facing change every (current Move squared / 10) hexes. (If you're measuring Move in feet, divide turning radius by 9; if Move is in inches, divide by 144.) Compute for both full Move and Sprint if you're often in a hurry.
The above ignores power and weight, so divide turning radius by Move Modifier. Dragonflies will cut impossible angles while winged elephants plow straight ahead.
Minimum turn radius should also be no smaller than linear dimension, unless you're walking or standing still and can pivot in place.
Runners need friction to make turns. A slippery surface should increase turning radius by some percentage. Weight matters: even on normal ground, a very light creature's weight might not provide enough friction with the surface to turn as sharply as a human. But that's too much detail to worry about.
The GURPS rules call for a control roll at -4 to reduce turning radius by one hex. GULLIVER's replacement: Make a control roll at -2 to cut turning radius up to x2/3 base value, -4 to cut radius to x1/2, -6 for x1/3, -8 for x1/5, -10 for x1/7, and -12 for x1/10.
Don't modify this control roll for encumbrance; power and weight were already accounted for in the turning radius.
Optionally, let any control roll failed or not bleed off 10% of your speed, or even 10% per 15° turn. Lots more if you crash and roll, of course.
More enterprising gamers can borrow the maneuvering rules from Vehicles 2E p. 147, setting MR equal to Move Modifier. Remember to multiply Move in yards by 2 to get mph. Modifiers to your control rolls for encumbrance, balance, etc. take the place of SR.
Fans of Vehicles and Robots can probably apply those books' rules to creatures in lots of other ways, but that's left as an exercise for the interested.
Acceleration is theoretically easy to figure from mass and power but for living creatures it's complex. Remember that the encumbrance rules assume some amount of power goes into supporting weight, with only the remainder available to move mass; detailed acceleration rules would have to take that into account.
You accelerate to full Move instantly, and can decelerate the same amount instantly. You can choose a Move maneuver, move your full Move, and on the next turn choose to not Move at all the normal GURPS way.
Achieving Sprint speed takes an additional second. Stopping after Sprint Move should also require that extra second.
As above, with one change: Enhanced Move (or its Super equivalents) doesn't factor into acceleration. If you have Move 18 with two levels of Enhanced Move and Move 6 without, you can achieve Move 6 on the first turn you run, Move 12 on the second, and Move 18 on the third, with Sprint Move coming on the fourth. This is why horses in the game take time to get up to speed.
The x2 Move multiplier GURPS uses for flying creatures can also be left out of acceleration, if the GM chooses. It'll take a bird two turns to accelerate to flight speed from a stop, or longer to reach a top speed further boosted by Enhanced Move.
Deceleration works the same, though slick surfaces may halve or otherwise reduce deceleration. Make a balance +2 roll to decelerate by twice your normal amount without falling. (Any rider on your back may have to make a Riding -2 roll to stay on, modified as the GM sees fit for how fast the actual deceleration is. Also add the rider's Half modifier for encumbrance.)
As above, but base Move on average speed over the turn. If you choose the Move maneuver to go from a stop to your full Move of 6, you move only 3 hexes that turn, and your full 6 the next. Deceleration works the same: you'll move 3 hexes on the turn you say "I stop". It's realistic, but detail-intensive.
Below is a look at all of the ways you can get about on land. Jumping and climbing are covered separately later.
A number of skills help creatures get about on land:
Jumping and Climbing are also useful skills on land.
You require skills just to get around: Crawling or Flopping. These affect your speed on land and are also used for control rolls. Either skill is P/E and defaults to DX-4. Other land performance skills are normally unavailable to you.
Aquatic creatures like lobsters and octopi can crawl slowly with Crawling. Creatures with no legs for land movement will have to rely on Flopping, and may receive a few points for Lame when removed from water (see Book 3).
You also take a -2 on combat and other athletic actions, including Dodge.
Then there are the hopeless ones. If you're terrestrial, take a -4 on any of the above skills for -1 point. Or for a max -5 points, take -4 on all of the above skills.
If you're non-terrestrial, a -1 point Incompetence gives you -4 on all land mobility skills: your Flopping, Crawling, and any others the GM allows you.
For most characters, running is what Move refers to.
Start with your Base Move and modify:
And there's your final running Move.
Running skill doesn't affect walking speed; Hiking does over long distances.
Use DX or balance rolls (with Half modifier for encumbrance) for control rolls while running.
Crawling here is abnormal movement: a human using arms, an octopus struggling on land, etc. For purposes of this discussion, normal animal movement is running, not crawling.
Start with your Base Move and modify:
Use Crawling (with Full modifier for encumbrance) to get over small obstacles or make other control rolls.
Use only x1/7 Move for adaptation, not x1/10. However, if you're not crawling with functional legs (a fish crawling with fins, a human with legs crippled), your bulk will drag heavily over the ground. Further halve your ST for encumbrance purposes!
This is the only mode of movement for creatures unadapted to land and without arms or legs for crawling. Treat as crawling in all respects, but halve ST (quarter it with the above advanced rule). Flopping skill replaces Crawling.
If you're light enough to flop at all, you can gain a little height and maybe get over those gunwales. Treat as a high jump using your lowered ST. But on the other fin, just moving in the right direction is a trick! Roll vs Flopping every turn to move in your desired direction; roll direction randomly on 1d if you fail. Don't be surprised if you head right back toward the fisherman.
Water movement is three-dimensional in a way even aerial flight isn't, if you're neutrally buoyant. We think of an "up" and "down" relative to the water surface and the sea bed, but swimmers are free to think differently divers have reported whales resting underwater pointed straight up!
All swimming movement is relative to any current; you're always carried along with it. Each turn, move your character normally from Point A to Point B. Now move her in the direction of the current at its Move, from Point B to Point C. This second movement is automatic. The actual path your character takes is a line drawn between A and C.
Good streamlining helps simply by letting you swim faster.
Note that Book 2's simple, cinematic rules (the GURPS default) make it easy to swim carrying an anchor, treating non-buoyant weight in water no differently from weight on land. Detailed, realistic rules make it very hard, multiplying non-buoyant weight in water by 5 for the lack of support underfoot. Your choice of rules will greatly affect the encumbrance component of Move below!
A number of skills help creatures get about in the water:
"Jumping" from the water into the air is simply swimming toward the surface and breaking through; see jumping rules. Let Water Acrobatics aid such leaps in the same way Jumping skill aids terrestrial leaps.
Aquatic creatures don't use the lame paddling techniques that humans call Swimming skill but CI to the contrary, they should have a Swimming skill that defines control over movement, just as fliers use Flight. (There's no exact land equivalent of Swimming or Flight, but land-dwellers deal with only two dimensions, not three. We'll let it pass.)
Let Swimming skill default to DX for aquatic races. It's useful in making a tight turn, threading a small gap at full speed, or recovering from a tumble in turbulent waters. But it doesn't affect Move for aquatic creatures; use the alternate skills above to go faster.
You require a special P/E skill just to get around. It's called Swimming, although it's not the same as the skill used by fish for you it's a hydro version of lowly Crawling! Let Swimming default to DX-5, and not ST. (Your ST affects performance through encumbrance.)
Take a -2 on combat and other athletic skills, including Dodge, while in water. Using long weapons will be even harder (see BS p. 91).
Other water skills are not available to you; the single Swimming skill affects your Move and determines your control in the water.
Water Acrobatics is an exception: humans do enjoy (or at least watch) displays of water ballet and synchronized swimming. But a land creature's version of Water Acrobatics would be less than the true aquatic version: an artistic Dancing skill, without acrobatic Dodges, water "walking", etc. For these, limit skill in Water Acrobatics to Swimming skill.
If you're aquatic, take a -4 on any of the above skills for -1 point, or -4 on all of them and any others the GM throws in, for a max -5 points.
If you're not aquatic, take a -4 to all water performance skills (usually just Swimming) for -1 point. This is a fairly common human Incompetence, and is definitely worth a character point. Our planet is three-fourths covered by water, and no adventurer is likely to avoid a dunk forever.
Regardless of what CI says, allow this Incompetence in racial designs too.
Aquatic creatures are as nimble in the water as we are on land:
Start with Base Move, and adjust as follows:
And there's your final swimming Move. Note that aquatic creatures will swim by default as quickly as land creatures run.
The Speed Swimming skill wouldn't affect slow movement underwater ("walking" speed), but an aquatic version of Hiking Long Distance Swimming does.
Use Swimming (with Full modifier for encumbrance) for control rolls.
Consider the effects of drag on Move. See Appendix.
For a non-aquatic creature, swimming is akin to an aquatic creature crawling on land. Still, high skill allows some impressive moves.
Start with Base Move, and adjust as follows:
Swimming speed for a human becomes Basic Speed/10, times skill/5. (If you like, rearrange that to Basic Speed/5, times skill/10, which more closely resembles the GURPS rule.)
A truly proper rule would probably modify thrust itself, not only Base Move, in some manner for Swimming skill; see the following advanced rules for one such suggestion.
Use Swimming (with Full modifier for encumbrance) for control rolls.
Use only x1/7 as an adaptation factor, not x1/10. However, you have poor thrust in the water: halve your ST for encumbrance purposes!
With this option, a human's swimming speed works out as Basic Speed/7, times skill/5. However, your lower thrust and the Book 2 rules will reduce your mobility further; average human Move with Swimming-10 will still be about 1 in the water.
This rule will let a little weight really drag you down, and will automatically give the average human some positive encumbrance from mass underwater. It's realistic: think how hard Dodges or other quick movements should be in water. Yes, you can make ballet-like acrobatic swirls in water that you could never duplicate on land but for an Acrobatics roll representing a quick motion, skill penalties make sense.
Example: You're a normal ST 10, 150-lb., MSR 15 human, with base Move 5 and Swimming-10. Underwater, WSR is 0. Using the advanced rule, you multiply MSR by 4 (2 for water, 2 for your human lack of flippers) to get 60. That gets you Light encumbrance in the water and a Move Modifier of x3/5.
To get actual swimming speed, multiply base Move by x1/7 for your human body ("Streamlining by Frigidaire") and by Swimming skill/5, and you have net Move of about 0.85. (That's close enough to 1, given the Table's rounding. The detailed Encumbrance Table in the Appendix would give you a net Move of almost exactly 1.)
Example: You board a pirate ship to join a melee on the decks, only to get a 20-lb. chain wrapped around your leg as you plunge into the drink. Multiply that weight by 10 (5 for water, 2 for your poor thrust) and divide by ST 10 to get WSR 20, and Encumbrance Factor x4. Your MSR is 17 (150 lbs. plus chain, divided by ST), x 2 for non-aquatic thrust, x 2 for water, x 4 for Encumbrance Factor = 272; you're struggling with X-Hvy encumbrance.
Drag: Again, consider the effects of drag on Move though most non-aquatic splashers can only dream of swimming fast enough to make it matter much.
Negatively buoyant creatures walking along the sea bed are essentially using land movement, though adding the rules for drag will really limit Move. Water will also affect weight, encumbrance and mobility.
But if buoyancy cuts your weight to one-fifth your mass or less, it's not easy staying put on the seabed. See the microgravity rules below, using Swimming instead of Free Fall for control rolls. Weighted boots may be a good idea.
Fliers operate in three dimensions like swimmers, though most don't gain the benefits of weightlessness. Wind works for fliers exactly as current does for swimmers: flight Move is relative to the air, not the ground. A tail wind adds directly to your speed over ground, and a head wind subtracts directly from it.
The below makes some distinction between true fliers with inborn flight abilities, and those who gain flying traits from technology, magic, or other means. A Super could fall into either category.
Book 2's simple, cinematic rules (the GURPS default) make flying as easy as walking for a winged human. Detailed rules will ground many human-sized fliers, multiplying WSR in air by 5. Advanced rules multiply WSR by 10, placing a very realistic ceiling on flight ability for creatures of any real size. Your choice of rules will greatly affect the encumbrance component of Move!
Skills to let you fly through the air with the greatest of ease:
Flight defaults to DX for flying races. Flying is different from land or water movement, in that non-adaptation doesn't leave you some reduced ability. You either can or can't fly.
Most fliers are terrestrial (or rarely, aquatic) creatures with the added ability of flight. A true aerial creature finds its home environment in midair, floating with gas balloons or flapping on magical wings that never tire. There are no Earth examples.
If you're a true aerial creature, take a -4 on any of the above skills for -1 point. Or for -5 points, you're just plain clumsy on the wing: take a -4 on all of the above and any others the GM tosses in.
If you're not a true aerial creature (which means all Earth fliers), take a -4 on all of the above skills for -1 point.
This is normal forward flight, using wings or some other form of thrust.
Start with your Base Move, and modify as follows:
Use Flight skill (with Full modifier for encumbrance) for control rolls.
Air resistance may slow you down. See Appendix.
This is forward flight using gravity to take you down and forward. You're not diverting thrust to offset weight (gliders don't have thrust!), so you're effectively in a slow free fall. Encumbrance doesn't affect forward speed rather, weight affects your speed of descent. (Note Book 2's suggestion for figuring a glider's encumbrance: use MSR x 10 for a glider, MSR x 50 for a parachuter, to figure mobility from the glider's limited ability to maneuver through position changes.)
Forward speed is likely a factor of your mass, drag, and gravity, but for simplicity, Base Move is used below.
Start with your Base Move, and modify as follows:
Use Flight (Gliding) skill for gliders and Flight (Parachuting) for parachuters. Let these cross-default at -2, and the latter cross-default to Parachuting at -2. Use the Full modifier for encumbrance for either.
Basing gliding flight Move on Base Move and linear dimension is a fudge that's filling a knowledge gap. For what's probably a more correct calculation, ignore all the above and let air resistance determine forward movement: gliding Move is ftv (see Appendix).
Going from a resting position to flight should require require a Change Position maneuver, which may take time for heavily encumbered fliers (use aerial encumbrance).
Takeoff difficulties really come into play for creatures that rely on airfoils, which let a too-heavy design fly (see Book 3). You don't get lift without forward speed but how do you get that speed when you can't gain the lift to fly? Do what heavy birds do: dive from a high cliff, reach flight speed, and pull out. A good flier design can also run fast enough to give the wings lift for take off. Facing into a strong wind helps too (remember, it's speed relative to air speed that counts).
A powered flier normally resists descent. An unpowered flier, or a powered flier diverting all thrust to forward movement and none to staying aloft, falls freely. See the Appendix to compute your terminal velocity (tv), which will be about 50 yards per second for a human.
Parachuting or Gliding abilities reduce speed of descent; see flight rules in Book 3.
Even if you're too heavy to fly, powered flight can at least let you fall more slowly through wild downward flapping.
At WSR 45 you apply just enough force in the upward direction to stay aloft (if not actually move anywhere). Set this upward force equal to (your weight x (45/WSR)); subtract it from your normal downward weight, and use this net weight to compute terminal velocity.
Sound awful? It is, so here's the work done for you:
Multiply tv by x1/7 at WSR 46, x1/5 at WSR 47, x1/4 at WSR 48, x1/3 at WSR 50, x1/2 at WSR 60, x2/3 at WSR 80, x3/4 at WSR 100, x4/5 at WSR 120, x9/10 at WSR 240, and x1 (i.e., no reduction) at WSR 480 or greater.
Flight rolls may be necessary to properly control your overfed-turkey descent and fully realize any tv reductions, as the GM decides.
Steal rules from Vehicles p. 155. On a dive, you'll keep gaining speed until you reach the faster of your diving terminal velocity or your weightless forward flight speed. If terminal velocity is the faster of the two, trying to flap your wings for additional speed will only slow you down.
Spread wings will also slow your tv through drag, if you're using that level of detail. For a really fast dive, make like a falcon and stow those wings.
Most fliers can "turn off" forward thrust and send just enough downward to stay aloft. That's hovering. Whether that's easy or hard for you is a matter of encumbrance. Larger birds may have encumbrance too high to fly without airfoil lift gained from forward movement; that removes the option of hovering.
Only a flier that can hover can move backward. Use the usual rule: double cost to enter a rear or side hex. See Book 3 for variations on direction and movement.
Soarers efficiently use warm-air "thermals" and other air currents to gain or maintain altitude with no significant effort. Book 3 makes Soaring a 5-point advantage for any flier.
If you need to maneuver, use the appropriate rules above for powered or unpowered fliers.
Assume a typical thermal will lift you two yards per second. Subtract your rate of descent from that; the remainder is the amount by which you actually rise. (Fast-falling gliders will simply have their rate of descent slowed by soaring on thermals, with no net rise.)
Even non-soarers should be able to benefit from thermals, but they're not optimized to take advantage of it: cut the amount of lift to half or less, and remove the innate ability to locate thermals.
A Flight roll should let you land safely in tricky conditions. Failure means you tripped and rolled, missed the perch, etc.
If you come in for a landing at high speed, you'll have to run with it. Make a balance roll to keep standing, at -2 if landing speed equals or is greater than your Move, -4 if twice as large, etc. Your legs can only decelerate so fast, too, so you may have to run and make rolls for a couple of turns. But a good flier does this all smoothly: make a Flight roll upon touchdown, and add the amount by which you succeeded to those balance rolls.
BS p. 139 offers fliers a +2 on Dodge, presumably for use of the third dimension. Change that to a bonus based on encumbrance-adjusted Flight skill: +1 Dodge per full 8 levels of skill, maximum +3.
There are also serious penalties on weapon use, Parries, and Blocks unless Flight skill is very high. Apply those penalties to fliers relying on technology (including magic spells), and ignore them for true fliers (those with flight traits).
Accuracy bonuses for aiming should be limited to Flight skill (or half Flight skill for strict GMs). Whether additional seconds of aiming gain a bonus or not is up to the GM; it's reasonable if the flier can hover smoothly (meaning No encumbrance or better and no wind).
Use the GULLIVER Step rules for fliers (Step = Move/5). Change Position is a free action in midair. Encumbrance for fliers uses the encumbrance rules from Book 2. Flight ceilings are discussed on BS p. 139; see Book 3 for help going higher.
Low gravity and vacuum are two features of space, but each exists fine by itself as well. The two are handled separately below. Combine the microgravity performance and vacuum performance rules, and you have space performance rules.
For simplicity, a gravity of 0.2-g or less is microgravity. That doesn't necessarily mean vacuum a 0-g space station will (one hopes) have atmosphere.
A creature in respectable gravity and atmosphere but with weight reduced to one-fifth or less by static lift also uses these rules! That's the problem with gas-bag dragons: they're okay on the wing, but goofily bouncy when trying to go about on foot.
A big effect of microgravity will be, of course, lower weight and encumbrance. That's a boon to many creatures until they launch themselves off the microplanet's surface. Read on:
Athletic DX in microgravity is limited by Free Fall skill. As CII p. 142 relates, athletic actions will also require a control roll vs Free Fall skill to avoid leaving the ground. Whether you come back down or not depends on how strong that gravity is, but the GM can rule that you're hanging free for any length of time, from a few seconds for an unintended bounce in low gravity, to infinity if you mistakenly launch yourself off your asteroid.
Creatures floating and unable to fly can't maneuver. Athletic actions will suffer a -4 or worse penalty, or be impossible. See CII p. 143 for some drastic measures that will allow you to maneuver in space.
Free Fall is the skill for both control and tricky maneuvers. There are no specific speed boost skills available, though Jumping helps you push off a surface at high speed.
For any creature that will spend some game time in space, an Incompetence with Free Fall is worth -1 point.
If you can fly in atmosphere or in vacuum, refer to the appropriate rules on flying or vacuum performance. Otherwise, air or space Move in microgravity is the speed at which you jump from or otherwise leave some massive object (but then what do you do?). See the jumping rules.
To pull yourself along a surface, you need to be able to grip it with arms or legs. Use an appropriately slow (but safe) Move. If you have to hurry, compute Move as below.
Start with your Base Move, and modify as follows:
Use Free Fall skill (with Half modifier for encumbrance). Modify skill by -6 for only one appendage keeping you anchored, no modifier for two, bonuses per Extra Legs for three or more appendages.
Flight in vacuum will be impossible or more likely, irrelevant in most games. But a space opera game can have mobile "space-wyrm" PCs.
For great cinematic fun, treat flight through vacuum exactly the same as flight in air. You'll turn, wheel, and dogfight just as you do in blue sky.
Despite the lack of gravity, cinematic space has an "up", at least when you meet up with other travelers. An approaching starship or fellow flier will always be seated on the same flat, invisible plane you're on (with the third defining point of said plane located somewhere in Hollywood).
You'll have a maximum Move that can't be explained (but so what). This is your normal flight Move, with weightless encumbrance. Huge bioships that could never fly in a gravity well will be able to fly (slowly) in space.
Realistically, you don't have a maximum Move in vacuum; you have acceleration. Your Move is unlimited, given enough time to accelerate. See Book 3 or Bio-Tech p. 136 to buy acceleration, which will be expressed as a multiple of g, such as 0.01-g or 2.0-g.
If there is gravity, you'll waste some power fighting it: use the Encumbrance Table to find your Encumbrance Factor from WSR, and divide acceleration by that.
Maneuverability is more tricky. Start with MSR 50, divide this by your acceleration, and look that up on the MSR column of the Encumbrance Table. For example, if you have 0.2 g acceleration, look up MSR 250 on the table: the equivalent of Extra-Heavy encumbrance. This won't affect your Move (you don't have a top speed, just acceleration), but it gives you modifiers for Dodge, quick acrobatic maneuvers, etc.
Creatures able to maneuver freely through space can use Free Fall as fliers use Flight skill and swimmers use Swimming skill; those native to space will have it at DX level by default. Adjust skill by the Full modifier for encumbrance when flying free.
Creatures that can accelerate in space will have whatever Move they can achieve through acceleration.
Your Move is your acceleration times the number of turns spent accelerating. Nothing else comes into play. You also get to ignore any effects of drag from air!
The big problem: you can only decelerate at the same rate. Make sure you reverse thrust and start slowing at the halfway point of your journey.
Use Free Fall skill (with Full modifier for encumbrance) for control rolls.
Creatures able to maneuver in vacuum should receive a bonus on Dodge, as aerial fliers do. Use a bonus based on encumbrance-adjusted Free Fall skill: +1 Dodge per full 8 levels of skill, maximum +3.
There is no universal "climbing" action. For an insect, a wall is just another surface to run on. For a human, wall-scaling requires a complete change of posture and a shift to using arms. The rules below determine climbing performance based on what's actually going on:
If the speed of a climb matters, convert the times given in GURPS to a Move score. Now multiply climbing that Move by Base Move/5, by Move Modifier, by Climbing skill/10, and by Linear Scale. Also double speed if you climb maintaining your normal posture (a squirrel, insect, etc.). Climbing speed may not be faster than running speed.
That adds much more variety to GURPS' climbing speeds, but won't necessarily give realistic results for very large and small creatures. When the numbers don't seem right, make arbitrary rulings, or head for the detailed rules.
These rules offer realistic handling of weight's role in climbing, but you'll want to use something quicker when the whole party starts climbing.
Climbing skill is used for control rolls and can also affect your speed. Base skill (including defaults) on DX, not ST. Your ST already plays a very important role via encumbrance.
Start with your Base Move and modify:
Multiply by another x1/10 if you're not terrestrial!
Roll vs Climbing -2, with Full modifier for encumbrance. But also modify for number of limbs used, per Extra Legs: +0 for two, +1 for three, +2 for four, +5 for five or six, +6 for seven to 10, and +7 for 11 or more. A human using four limbs gets a +2.
Even the lightest insect will always be slightly less maneuverable than it is on the ground, as it always needs to maintain grip on the surface. No matter how good a climber you are, lose contact with the surface and you will fall.
Extreme maneuvers, including attacks and active defenses, force a Climbing roll to avoid falling if the slope is 45° or more, at -3 for every full 15° greater. That goes for surfaces between 90° and 180° too, in which case you're dangling from an overhang.
GURPS suggests control penalties for the type of climb, but these rules already take care of that through encumbrance and the above control penalties. Add other modifiers as appropriate: say, a penalty for dress shoes instead of proper footwear.
A bare tree provides no holds for a dog, poor holds for a human (shinnying up), good holds for a squirrel's tiny paws.
On some surfaces, human hands might be able to grip, while feet couldn't gain purchase unless those feet had claws. Considerations like this replace GURPS' +2 on Climbing for claws.
Steep climbs involve a combination of pushing and pulling. Climbs may suffer large penalties or be impossible if your limbs can only push you, not pull you. Even easier climbs may be hard without limbs "on top" for balance, guidance, and pulling.
The above rules assume precarious footing. If weight is able to rest on sturdy footing below, such as a human on a ladder or stout branches, halve any increases in encumbrance level. Extreme maneuvers take a +3 bonus on control, instead of the penalties above.
Adjusting WSR for slope realistically slows light creatures little, heavy creatures a lot. Even walking up a slope is a bear for big creatures.
Humans in vertical climbs have to rely on finger and toe power instead of leg power hence the adjustment to WSR. At Super-Heavy encumbrance you're trembling and running out of power quickly; at Extreme, you can't hold on.
But with two multipliers to work with, just eyeball a level of encumbrance with no calculation if it's a tense game moment. And any time it seems a character should be able to make a climb despite a too-high WSR, call it Extra-Heavy or Super-Heavy encumbrance and get on with it.
Climbing Move should not exceed running Move. Note that if you have good footholds and no posture change, you essentially are running: you use regular running enhancements instead of climbing enhancements!
Let Clinging confer Good holds on any surface, even glass. Your Climbing automatically defaults to DX or to 16, whichever is higher. The worst Move adjustment you face for adaptation is x1/2! See Book 3.
Swinging from your arms requires proper body form and at least two gripping limbs of decent length. Use x2 as the WSR multiplier for slope. Move multiplier for general adaptation is x1/5. Control rolls are as above; with only two limbs used, that means -2.
The Brachiator advantage makes things much easier. Change the Move multiplier for general adaptation to x1/3. Control rolls are at +2 when swinging (i.e., base -2 for Climbing control roll, +2 for Brachiator, +0 for two limbs, equals net +0). You also get Climbing at DX and Acrobatics at DX-2 for free.
A master vine-swinger will combine Brachiator, a good WSR, extra gripping limbs for better control rolls, and Enhanced Move (climbing) for additional speed. Long arms would explain the Enhanced Move.
Climbing skill includes the ability to climb ladders and rappel down walls things a mountain goat, renowned as a climber, could not do. Many climbs are simply out of reach if you don't have gripping limbs.
Much of what we call "climbing" in nimble animals is simply walking up slippery slopes and jumping from rock to rock. A mountain goat doesn't rely on Climbing skill so much as it does on strong legs for good jumping distance and light natural encumbrance, good Jumping skill, Sure Footing (rocky ground), Improved Balance, and plenty of Survival (Mountain) to judge what is and isn't safe.
The jumping rules on BS p. 88 give quick answers, and that's good. But they don't work at all for low ST scores. How far can your Cidi jump? He can't jump at all, period.
Weight and size, important factors in real-life jumps, are left out of the rules. There's an option for working encumbrance into the equation, but it penalizes a low ST a lot and a high ST a little, even though the effects of an equal level of encumbrance should be proportional in either case.
But then Jumping skill throws out ST anyway: if both have Jumping-16, a ST 4 weakling and a ST 15 Olympic powerhouse will jump the same distances. Give the weakling a skill of 17, and he takes the match.
You get the idea. Below is an improved (and very accurate) look at how creatures jump.
Below is a simplification from the detailed rules not too precise, but good for a quick gaming style:
Broad jump: Your base jumping distance in yards, Jd, is Move Modifier x Linear Scale x enhancements. (ST doesn't appear here; it's already figured into your Move Modifier.)
Enhancements include appropriate multipliers for Poor Jumper, Enhanced Jump, and Super Jump.
High jump: As above, but jumping height is half Jd.
If you run, add 1/2 forward speed to broad jump distance, or 1/18 your forward speed to high jump height (that's 2" per yard of Move), using the same units.
You need to run for a second to achieve full speed, or longer to achieve sprint speed. For humans, the above rule will generally let a sprint double your jump height, and almost double distance.
Add your leg length (a yard for a typical human) to broad jump distance. Add half your leg length to high jump height not for purposes of reaching higher (as in dunking a basketball), but for purposes of clearing an object below.
Multiply distance or height in yards by 3 to get feet, by 36 to get inches.
Example: An average human has Move Multiplier x1 and Jd 1, for a base standing broad jump of 1 yard. Add a yard for leg length, for a 2-yard jump. If running at Move 5, add 2.5 yards to base distance, then a yard for leg length, for a 4.5-yard jump.
Base standing high jump height is half Jd in yards, or 18". Add half a yard for leg length: you can clear a 36" height. Running, you can clear a height of 46".
Example: As above, but with Heavy encumbrance and Move Multiplier x2/5. Jd is only 0.4, for a base standing broad jump of 0.4 yards. Leg length adds a yard, for 1.4 yards. If running at Move 2, add half Move for a 2.4-yard jump.
Base standing high jump height is half Jd in yards, or about 7". Add half leg length to clear a 25" height. Running at Move 2, add another 4" for Move, to clear a final 29".
Example: A 2" PC is one-thirty-sixth human height with Move Modifier x7 from negative encumbrance. The player jots down a Jd of 7 x 1/36 roughly 0.2. With no running start the PC can jump 0.2 yards or 7.2 inches long, plus an inch for leg length, for 8.2 inches. Or he can clear an obstacle 4.1 inches high. Either result is very impressive in relation to height!
Borrow the rules for Extra Effort and the Jumping skill from the detailed rules below.
For quick gaming, simplify all jumps into three types: those that obviously succeed for the character, those that obviously fail, and all "iffy" jumps in between. Resolve the iffy jumps as a simple yes or no: success or failure on a Jumping, DX, or Extra Effort roll. This plays quick and fun.
As in the throwing rules that follow, GURPS combat conditions are the default for these rules: you hold back a bit, keeping yourself ready to defend yourself or otherwise act immediately following the jump.
But you'll more often want to put your full effort into a mighty leap. You can't hold anything back when crossing the Chasm of Doom; nor do track and field contestants need a semi-defensive posture for the high jump!
The rules below take care of this with a simple bonus to your distance for All-Out action, in which you spend your whole turn jumping and don't get an Active Defense. Keep the choice in mind when making your jumps.
Jd is your base jumping distance in yards. It's how far your center of mass moves in a jump, and is calculated very realistically as follows:
The second equation places an arbitrary maximum speed on muscle contraction and resulting distance; see the Appendix for details. It will usually come into play only for very small creatures.
Jd is 1 for an unencumbered average human, 0.9 for a human approaching Light encumbrance. For heavier loads, Jd is roughly equal to Move Modifier from encumbrance, if you want quick approximations.
Example: A Speed 5, ST 12 human PC weighing 180 lbs. and lugging 45 lbs. of gear computes Jd as the lower of 12 x 1 x 15/ 225 = 0.8, and 5 x 1 = 5. Use Jd 0.8.
Enhancements: Enhancements refers to multipliers for Poor Jumper, Enhanced Jump, or Super Jump; these represent mechanical efficiency, unusually strong or weak jumping muscles, or even magical aids.
Linear Scale: Book 3 offers Long Legs and Short Legs, but for simplicity these don't automatically affect jumping distances; use overall Linear Scale. If you want to account for the effects of odd leg lengths, add Enhanced Jump or Poor Jumper.
Below are several factors that add percentage bonuses to Jd. These are additive: a 20% bonus for Jumping skill and a 30% bonus for All-Out action combine to a 50% bonus.
While the rules use your full ST stat and precisely-measured angles to determine distance, they also assume that actual performance falls short of potential. Jumping skill simulates optimal timing, angle, and power.
Don't adjust Jumping skill for encumbrance here; weight and ST were already fully accounted for in basic distance.
Rolling: If you prefer, make the above a roll vs Jumping. Success by 2 or less increases Jd by 10%, and every additional 2 full levels of success increase Jd by an additional 10%.
Failure offers no bonus. A critical failure means you slip or fall. (Taking the automatic bonus is far more certain, but rolling is the way to go when shooting for a record jump!)
Skill and ST: Don't substitute Jumping skill for ST, here or anywhere. Don't base Jumping skill on ST, either. Jumping represents the coordination and technique to eke the most distance out of a jump. ST is already properly accounted for on its own terms.
Default: For any use of Jumping, let the skill default to DX -4 or Acrobatics -4. Do not default to ST.
If you're not in combat or otherwise don't need to maintain a defensive posture, put everything into the jump. That's the normal way to jump, whether you're on the sports field or leaping a dungeon chasm.
Just as in an All-Out Attack, you use your whole turn and do not get an Active Defense.
For quick play, just tack an extra one-third to base jumping distance, or replace the x15 in the Jd equation with x20.
Beyond All-Out action, GURPS allows Extra Effort. In the GULLIVER rules, Extra Effort allows a roll vs HT, modified for Will:
Angle affects your distance and height:
Long jump: The best distance you can achieve is often with a 45° angle broad jump. Base distance in yards equals Jd. Height will be one-fourth that.
High jump: The best height you can achieve is with a vertical (90°) high jump. Base height in yards equals half Jd. You achieve no horizontal distance.
Jumps to clear an object do require forward momentum, though. Assume 60° if you care for the extra detail.
Any angle: To take all jumps into consideration, multiply height and distance as follows:
Example: With Jd 0.8, the above encumbered PC can broad jump 0.8 yards (2.4 feet), or high jump half that. Sounds too low? Read on:
This is the classic way to boost distances, although it's hard to convert the kinetic energy upwards. Increase your performance in one of the following ways:
Distance: Add your forward Move x 1/2 to distance;or
Height: Add your forward Move x 1/18 to height. (That's 2" per yard of Move.)
For standing jumps, heights and distances computed so far appear too low. That's because they estimate how far your center of mass moves, and they're good estimates at that.
But we measure jumps for ourselves differently, placing importance on body position. Even without a jump, a big stride alone will carry you a yard or more! Long jumpers take off with feet far to the rear and bring them far forward for landing; this footprint-to-footprint distance is what we measure. Likewise, lifting your legs up doesn't raise your body any higher, but does let you clear more height below when jumping over something.
You can add part of your leg length (call it a yard for a tall human) to your height cleared or distance:
Ideal form: If you can meet three conditions All-Out action, significant forward momentum (Move at least equal to twice Linear Dimension), and an extra Jumping roll to fine-tune your position you can achieve even better form:
Add skill modifiers for encumbrance to these Jumping rolls for proper position and landing.
Be sure to be consistent with units! When measuring base distance in yards, adjust for Move and leg length using yards. Or convert Jd to feet, and make adjustments using feet.
Below are examples, rounding small fractions:
Example: The above PC with Jd 0.8 can perform a standing broad jump of 0.8 yards. But he'd normally use All-Out action, boosting his Jd 0.8 by 30% to 1.04 (let's call it Jd 1).
To either of those base distances, he can add a yard for leg length.
A running start will further help. Assume Move 4. Start with the above Jd 1, and add half Move (2 yards) to get 3 yards. Add an extra yard for leg length to get 4 yards, or a yard and a half with ideal form (don't forget the required Jumping roll) to get 4.5 yards.
Example: The same PC makes a high jump. Start with that All-Out Jd of 1: he can jump half a yard high.
To jump over a table, let's get detailed and assume a 60° angle: the PC can only jump x3/8 yard, or 13.5 inches high, plus another half yard of leg length to clear 31.5 inches.
With a running start, he can add another Move/18 to height, or 8 inches. Total height cleared: 39.5 inches.
Example: A 2" microhuman weighs about 5 thousandths of a pound and has a Load ST of about 0.01. Linear Scale is x1/36. Speed is 6 and Move is 1.
Jd is the lower of 0.01 x 1/36 x 15 / 0.005 = 0.83, or 6 x 1/36 = 0.17. Go with Jd 0.17. Adding 30% for All-Out action, the tiny man's standing broad jump is just under 8 inches, plus an inch or so for leg length. With a running start, he'll make a leap of over two feet.
You can easily eyeball his vertical high jump. If his standing broad jump is 8 inches, height with vertical jump will be half that, or 4 inches. Add Move/18 = two inches height for a running start. That's six inches high, something like 6 yards for a normal person!
If leaping over an object, the microhuman would use a flatter angle (say, 60°), and add half an inch clearance for leg length (or add a full inch with a Jumping roll and ideal form).
Example: You're an Olympic-class jumper: ST 16 (at least in the legs), 175 lbs., Move 7.5 (9 sprinting), and Jumping-18. Legs are a yard long. Your Jd before skill is 1.37.
You're shooting for the gold. Your jumps naturally take the 30% Jd bonus for All-Out action. You also roll vs Jumping for a boost from skill: say, a 50% bonus for rolling under your skill by 10 . And let's say your Extra Effort roll adds another 20% for phenomenal exertion. Total bonus: 100%. Your Jd becomes about 2.75, which for a 45° angle means 2.75 yards so far.
You run your fastest and add 4.5 yards (half your sprint Move) to distance. A successful Jumping roll for ideal form lets you add another yard and a half for leg extension. That brings you to 8.75 yards. Not the world-record 9.4 yards (8.6 meters), but getting there!
Example: Now you go for the high jump. Let's use the same über-boosted Jd of 2.75.
Assuming a 60° angle is what's needed to clear a bar, multiply Jd by x3/8 to get a height of 1.03 yards, or 37 inches.
Your Sprint Move adds 9/18 yards, or 18 inches, giving you 55 inches. A Jumping roll and ideal bar-clearing form give you an extra yard for leg length, for a final 91 inches very impressive, though a bit short of the world-record 96.5 inches (2.45 meters).
The above is all pretty involved, but once you have Jd, you can quickly compute basic high jump and broad jump distances, add free bonuses for leg length, and write those down as distances you can always make without Jumping rolls.
You won't often need to know your exact performance involving Jumping rolls, running Move, and other bonuses; if you do, jot the results down for recycling.
When making sports jumps, don't forget all applicable bonuses from Jumping skill, All-Out action, Extra Effort, and Move (sprinting is preferable). Also use the added Jumping roll for ideal form, letting you get maximum leg extension in a broad jump or flat-on-back position in a high jump.
Some jumping actions can be treated as maneuvers. Examples are Pole Vaulting and Triple Jump (below). The rolls to achieve ideal form (and max leg length bonus) in regular jumps can also be treated as a Hard maneuver (use separate maneuvers for ideal form in a high jump and ideal form in a broad jump), limited to Jumping skill +4.
Pole vault rules might work something like this:
Pole Vaulting is a Hard maneuver defaulting to Jumping -4 and limited to Jumping skill. Take a good running start, plant the pole, and make a basic high jump. If that jump plus your height equal a certain percentage of the pole's length, you achieve "lift off".
Unlike a regular high jump, vaulting converts forward movement to height well. Going "over the top" would require a Pole Vaulting roll, and presumably some combination of forward speed and initial high jump distance sufficient enough to carry you the height of the pole. A properly flexible bar makes all this easier. Add the leg position rules for high jumping to clear a bar. After that, you just need to survive the trip down.
Not only do you gain great height with a vault, but your ground distance will cover up to twice the length of the pole, plus the extra leg length from the broad jump rules.
Turning this into workable rules is left to gamers with experience in vaulting.
The triple jump is a series of three running broad jumps. Momentum is lost between jumps, and the net distance is about twice that of one jump.
For more detail, make Triple Jump an Easy maneuver of Jumping, defaulting to Jumping -2 and limited to Jumping. Make your first jump normally. Subsequent jumps use Triple Jump rolls to boost Jd, but reduce distance to x2/3.
Total the distances for the three jumps, and see whether you won the meet.
Can you can dunk a basketball? Take your own height, plus about two-thirds your arm length, and add running high jump height (without any leg length bonus; we're not measuring height cleared underfoot). Is the result a good foot higher than the rim? SLAM!
No special maneuvers are needed for the jump, but a Basketball skill roll ensures that you slam the net and not the rim. Roll at +2 if your hands are large enough to "palm" the ball.
You won't often care what the speed of a jump is, but there are situations where it's an interesting bit of trivia.
Compute jumping velocity, Js, as the square root of (Jd x 10). Js is in yards per second. Multiply by 2 for mph.
The average human will have Js of about 3.6 (using All-Out action), which matches observations.
Your vertical speed upon landing is the same as it was at takeoff. GURPS assumes that any jumping ability you have lets you take the shock of both takeoff and landing, which implies that you can "absorb" a fall of velocity Js (or a fall of height equal to your maximum high jump) if you can land on your feet. A Jumping roll may help you do that.
Whether the surface you land on can withstand the impact of your super-leap's abrupt end is another matter.
Your acceleration in a jump is roughly Jd / Linear Scale, expressed in gravity (g). That's about 1.3-g for the average human (using All-Out action), 1.5-g and up for a more athletic individual.
Acceleration is incredible in tiny jumpers and thanks to great power-to-mass ratios, they have no trouble handling it.
How long will Captain Cricket be in the air during a city-spanning leap? Say Cap leaps 1000 yards in a standing broad jump, hitting a height of 250 yards. The distance an object falls in yards in a given length of time, ignoring air resistance, is equal to
where acceleration is about 10 yards/sec/sec in earth gravity and time is measured in seconds. For jumps, start with falling distance and solve for time:
Time spent in the air will be twice that, as it takes the same amount of time to go up.
Cappy C's fall of 250 yards takes about 7 seconds so our hero must have spent 7 seconds going up and 7 down, and during those 14 seconds had a speed over the ground of about 1000 yards/14 seconds = Move 71!
Cap has a Jd of about 1000, and a Js of 100. The hero's many levels of Super Jumping apparently confer the ability to resist the 1000 or so g's he pulls in a leap. (It's up to you whether that lets him survive the same obscene acceleration in a malfunctioning warp cruiser.)
Note that the above results aren't entirely realistic, as a fall of over 100 yards or so should take air resistance into account. Of course, that same air resistance should also work against Cap making that 1000-yard leap to begin with. See the Appendix if you really want to play with drag, but it's detail overkill in a highly cinematic game of half-mile hops.
Takeoff speed is unchanged by gravity (you still accelerate the same mass), but the distance you travel will vary greatly. Divide distance and height by local gravity. ("Hang time" will change too, when you recalculate using new distance fallen and new acceleration. But you'll get the same result by dividing 1-g hang time by the new gravity.)
In zero-g, you can jump off from a wall or asteroid with a Move equal to Js and with an infinite jump distance, you'll go forever unless something stops you! Be careful, spacefarers.
You can make a few good jumps in quick succession through special techniques, such as the triple long jump. But otherwise, try hopping all the way down the street. It doesn't really work, does it? It's very fatiguing, and decent jumps seem to require a second or so between leaps to get into position.
Without those readying periods, let's say the best you can do is half-distance jumps, with extra distance or height for leg positioning halved as well. Treat as sprinting for fatigue purposes.
Book 3 offers a Jumper advantage for 5 points, equipping you to jump continually without readying yourself between leaps. This is appropriate for creatures like a kangaroo, which efficiently regains much of the energy of a jump upon landing, stretching powerful elastic tendons and leaping again right away.
You can't change course or stop in mid-jump (unless you can fly!), so you're not very maneuverable. Enemies may have a hard time hitting you if you jump fast and far, but if they do draw a bead, you Dodge at -4. (Unless you jumped with All-Out action; sorry, no defenses.)
A good jumping ability can help a tiny creature avoid the stomps of large foes. See Book 5 for rules.
Swimming fast and breaking through the surface of the water isn't really a "jump", but the effect is the same. Use the detailed jumping rules, with this easy (and accurate) simplification:
Js is your Move in yards at the time you leave the water. Jd is (Js squared) / 10; figure your height and distance normally from Jd and your angle. Jumping skill won't help (although Extra Effort rules do allow you to increase Move, which will help here). Don't add distance for movement (that's already the base for the leap). Body position, too, won't matter for a leaping fish.
That's about it. If you're a flying fish, spread your fins and enjoy the glide down.
As described above, forward movement is a great way to add to either your distance or height in a jump. Further complications:
Splitting Move: Go ahead and split your forward Move between extra distance and extra height to get precisely the jump you want. For example, you might split a Move of 7 into Move 4 for extra distance and Move 3 for extra height, resulting in an extra 4 x 1/2 = 2 yards of distance, and an extra 3 x 1/18 = 3/18 yard or 6 inches of height.
Calculating distance: Adding half Move to distance is a simplification. A correct calculation would determine additional forward distance by multiplying time spent in the air (twice the time required to fall from height of jump) by forward Move.
Boosting distance by (Move x 0.9 x square root of jump height), where Move and height are expressed in yards, is a fairly accurate approximation. You'll notice that using this rule, a jump steeper than 45° may provide optimal distance in a running broad jump!
Combined with the above suggestion for splitting Move between extra height and extra forward distance, you can really get some use out of your calculator. Save it for adventures surrounding athletic meets.
Lumping all PCs into "Linear Scale x1" works against the tall ones. For ultimate detail, come up with exact leg lengths for use in high jumps and long jumps, and use "leg length in inches / 34" or some such number in place of Linear Scale. (Check your Levi's if you're not sure of length.) It's overkill, but fun if two PCs decide to settle a score through a mini-Olympics.
Any jumper loses a bit of efficiency to drag, though there's no need to worry about this unless the effect is big which it is for really tiny jumpers. If you want to factor it in, see the Appendix.
GURPS' rules for throwing (CI p. 11) compute distance as ST times some multiple, and that multiple itself varies with your ST. This double-counting of ST isn't quite right. Further, the rules don't mesh with GURPS' rules for weapon ranges, which use ST times a fixed multiple.
Below is one set of rules that handles spears, sacks of concrete, two-handed lobs, or blazing baseball pitches, while remaining very simple for typical combat throws.
The rules use the same basics as the jumping rules. Power vs the mass to be moved determines the acceleration of the arm, and the arm's length the distance over which acceleration occurs. These determine the speed and distance of the released projectile.
When rules below call for penalties on throwing actions, note the distinction between TH penalties and skill penalties. A TH penalty only affects TH; a skill penalty affects TH and anything else determined by skill level, such as bonuses on distance.
The GURPS rules work fine for human ST ranges. However, the detailed rules below are arguably simpler! For most situations human-sized characters throwing typical weapon-like weights they boil down to this:
There's your maximum distance in yards no separate range multipliers for each and every weapon, no turning to CI tables for other objects.
The following rules make arm mass part of the performance equation, just as body mass is in jumps. Arm mass sets an important limit on how fast you can hurl a tiny rock.
Only a small portion of arm mass matters here, not the whole limb, and approximating that portion from body mass is fine.
Simple mass: Use 3 lbs. for any human-sized character. For other Sizes, multiply 3 lbs. by Volume Scale.
Detailed mass: Base arm mass on total body mass:
Use (body mass / 50) lbs. as arm mass.
Round to the nearest pound, or to the nearest half pound (or other significant fraction) for small beings. For the average human, it's an easy 3 lbs. Mass of carried items won't matter here (except mass of the arm's armor, gloves, etc., if you really want to overdo the detail).
Advanced mass: As above, but take a good guess at mass for short or long arms. Multiply mass by the arms' Linear Scale (relative to the character's) if they're long or short in one dimension only. That's unlikely, though; assuming some change in thickness too, multiply by the square of that Linear Scale difference, or its cube(!) if the arm is equally scaled in every dimension.
Compute Td, your base throwing distance, as follows:
Td = lower of:
The second equation places an arbitrary maximum speed on muscle contraction and resulting distance; see the Appendix for details.
Unfortunately, Td isn't as useful to jot down on the character form as Jd was. That's because the weight of what you throw will often change. But do write down Td for any items the character will throw often, like favorite weapons or one-pound rocks (gosh, they're everywhere!), to avoid calculation during play.
Example: Your human PC throws a 1-lb. rock. Use the typical human 3 lbs. for arm mass. With ST 10 and Speed 5, Td is the lesser of (10 x 10 / (3 + 1)) = 25, or (5 x 1 x 10) = 50. Use Td 25.
Enhancements: Enhancements are left out of the above formulae, as these are rare in throwers. If you like, though, let Poor Thrower, Enhanced Throwing, and Super Throwing have the same distance effects and cost as their jumping counterparts. A level of Enhanced Throwing would multiply Td by 2.
The power of an arm to throw is generally the same as its power to strike. If you bought an arm with weak striking power, it will automatically have low ST available for throwing, without any addition of Poor Thrower.
Linear Scale: Book 3 offers Long Arms and Short Arms. The latter decrease throwing distances, but for simplicity, Long Arms don't automatically boost distances. Add Enhanced Throwing if they do.
Two-armed throws: One arm can only throw weight up to your maximum one-handed lift, or Load ST x 6 lbs. Two arms let you pick up and throw an item of up to Load ST x 25 lbs., per GURPS.
To calculate Td for two arms, use the method above but give Load ST a 50% boost in the first formula. (For simplicity, continue to use the mass of one arm.) On the other hand, speed suffers a lot. Divide the second formula's value by 5.
Example: That same PC throws a 1-lb. rock two-handed. Td is the lesser of (15 x 1 x 10 / (3 + 1)) = 37.5, or (5 x 1 x 2) = 10. Use Td 10.
That's a dumb way to throw a small rock, but a 20-lb. weight will fly farther with two hands than it would with one. Td is the lesser of (15 x 1 x 10 / (3 + 20) = 6.5, or (5 x 1 x 2) = 10. Use Td = 6.5.
More arms: If you have more than two arms that can get in on the throw, add another 10% to Load ST per extra arm in the first formula, but reduce Speed by another 5% per extra arm (down to a minimum of 10% remaining). You're better off not using those extra arms unless the load is really heavy.
Maximum lift with many arms is Load ST x 25 plus 10% per arm above two.
Example: The above PC sprouts two more arms to throw a 50-lb. rock. Load ST is boosted a total of 70% to 17; Speed is reduced another 10% to 0.5. Td is the lesser of (17 x 1 x 10 / (3 +50)) = 3.2, or (0.5 x 1 x 10) = 5. Use Td = 3.2.
Below are several factors that add percentage bonuses to Td. These are additive: a 30% bonus from skill, a 30% bonus from All-Out action, and a 10% bonus from Extra Effort combine to a 70% bonus.
As with jumping, assume that calculated Td is for a less-than-optimal throw. Throwing skill will raise Td.
Throwing skill: GURPS' bonus of skill/6 to ST doesn't scale well over the power range. Percentage bonuses do. It's also more realistic (and simple!) to give bonuses only for significant skill levels, not beginning at a measly Throwing-6. GULLIVER's rule:
Increase Td by 10% for every 2 full levels of skill over 10.
The Throwing skill covers a very wide range of techniques, hence the P/H rating. All other throwing skills are P/E.
Rolling: If you prefer, make the above a roll vs Throwing. Success by 2 or less increases Td by 10%, and every additional 2 full levels of success increase Td by an additional 10%.
Failure offers no bonus. A critical failure means you slip or strain yourself! (Taking the automatic bonus is far more certain, but rolling is the way to go when shooting for a record toss!)
Other skills: The GURPS rule is that only Throwing skill lets you boost distances, as well as roll TH to throw any object. Other combat throwing skills only let you roll TH with the appropriate weapon. That's easy to play, but provides very poor incentive for learning any throwing skill except Throwing.
It's more fun and realistic to do the following:
Let any throwing skill boost distance in the same manner as Throwing, for the appropriate thrown object.
This means that unless specified otherwise, combat throwing skills (Knife Throwing, Spear Throwing, etc.) gain the same Td bonuses as Throwing when used with the appropriate weapon. (Throwing skill still remains a heck of a bargain, though, as it covers any object.)
GURPS disallows AOA with throws. That means that instantly after any throw, you're fully recovered and ready to nimbly defend against attacks which doesn't sound too likely when you're hurling your hardest.
Allow All-Out action with throws. Disallow the +4 TH option, and the two-attack option (unless the thrower has knives in each hand, or a magic spear that "reloads" instantly). But you should be able to throw harder with an all-out heave the equivalent of the damage bonus option. The rule:
Increase Td by 30% for All-Out action.
For quick play, call this a one-third bonus to base distance.
Beyond All-Out action, you can further increase range through Extra Effort. In the GULLIVER rules, this allows a roll vs HT, modified for Will:
"High throws" and "broad throws" aren't an issue. You'll generally use your optimal angle, about 45°. This gives you maximum distance, which is Td yards. Height of the throw, should you need to know, will be one-fourth that distance.
A rock thrown straight up will achieve a height of half Td in yards (or less, as we're not built to throw that way), and no horizontal distance.
If angle does matter, use the trajectories from the jumping rules.
Example: With Td of 25, you can throw that rock 25 yards out, or about half that distance straight up. All-Out action will raise distance another 30% to almost 33 yards; skill will raise it even further.
Example: Grunt, a Size +2 Giant, throws a 10-lb. hammer one-handed using Axe Throwing-14. With Speed 4, Load ST 52 and arm mass of 1360/50 = 27 lbs., Td is the lower of 52 x 2 x 10 / (27 + 10) = about 28, and 4 x 2 x 10 = 80. Use Td 28.
Add 20% for skill, to get a Td of 33.6. That hammer flies about 34 yards.
If Grunt hurls hard instead of cautiously, he can add another 30% to Td for All-Out action, for a total bonus of 50%. That boosts Td from 28 to 42, for a 42-yard throw. When a 10-lb. hammer comes flying nearly half the length of a football field, surviving PCs will learn to stay far away from Giants.
Angle is important in one arena: combat. Chucking a javelin at a nearby foe will mean a very flat angle, and a miss won't fly far.
A 15° throw has only half the range of an optimal 45° throw. Call this halved, flat-angle Range your 1/2 Damage Range.
Targets at 1/2 Damage Range or closer can be hit with fairly flat throws. Targets outside your 1/2 Damage Range require a higher angle. That turns the attack into indirect fire, which is why you lose your Acc bonus! Lobbing a weapon high and hoping it comes down on your foe is not an easy task. The rule:
For throws steeper than 15°, drop Acc and take a -1 TH per additional 15° angle.
This is in addition to normal penalties for distance or other factors. (It may be possible to reduce this penalty via a Hard "Indirect Fire" maneuver, if the GM allows.)
Example: Your throw has a maximum distance of 20 yards. A flat throw of 10 yards or less suffers no penalty.
Any farther throw is outside 1/2 Damage Range and requires a high arc, losing Acc and taking a TH penalty. A full 20-yard throw requires a 45° angle, taking -2 TH with no Acc.
Note that there are no rules for determining the distance at which air resistance would actually halve the impact and damage of a missile; for simplicity's sake only, GURPS takes the distance at which Acc is lost from a high angle, and gives it double duty as 1/2 Damage Range.
Misses: How far does your missile fly if you miss your target? If it matters, use this quick rule of thumb: Any miss will fly twice the target's distance from you, but not more than that throw's maximum distance and not less than half its maximum distance.
Example: Your spear has a maximum distance of 20 yards. Since your target is within 1/2 Distance Range (10 yards), you use a flat (15° or less) throw with a maximum range of 10 yards.
Where will the weapon land if you miss? It'll sail twice as far as the distance to the target, but not less than 5 yards, and not more than 10 yards.
You'll hurl that javelin farther by running. This doesn't boost Td itself, but rather the speed your missile flies in the direction of your movement. For simplicity, this consideration is best gamed as an easy distance bonus. The rule:
Add twice your Move to distance, using the same units, up to double distance.
If you only Step and Attack, you may add twice your Step distance to throwing distance, if that little bonus is worth considering.
Skill penalties: GURPS looks down upon full Move followed by an attack. This should be possible with a throw, but difficult: apply a -4 skill penalty for all purposes, including TH and distance bonuses. (Some throwing skills, like the Javelin Throw of track and field, can run and throw without loss of distance.)
You can throw this way while running at full Move, but throwing from a Sprint should be an uncoordinated mess. Apply an additional penalty of -2 or more.
When making sports throws, don't forget all applicable bonuses from Throwing skill, All-Out action, Extra Effort, and possibly Move (but not sprinting; the skill penalties are very high).
It may or may not be in the rules, but allow Grenade/Rock Throwing as a combat throwing skill for any small, roundish object, whether rock, grenade, or baseball. (That's for a "generic" throw, not a pro-league wind-up and pitch.)
The Throwing skill works here too, of course, but Grenade/Rock Throwing is a legitimate skill. A soldier is likely to learn to throw grenades or a country boy, toss rocks without mastering javelins, axes, and shuriken at the same time.
Quarterbacks use a versatile throwing skill allowing quick, flat passes or the long-range "Hail Mary". A Football Throwing skill, similar in all ways to a combat throwing skill, works well.
Distance throwing competitions can involve very specialized techniques designed for maximum speed and optimal angle. In general, treat these as unique P/A throwing skills, with larger distance bonuses than those from combat throwing skills or Throwing. The rule:
For specialized distance skills, increase Td by 10% for every level of skill over 10.
Rolling: If you prefer to roll vs skill, every point of success increases Td by 10% (treat success by 0 as success by 1). Failures work per other throwing skills.
Drawbacks: Specialized distance skills rely on lengthy spinning or other routines, and users train only to achieve fixed angles, not to hit targets. In short, the skills aren't made for combat (except in cinematic games!). Require a second of Readying to use the skills, and apply a flat -4 TH when aiming at targets. Instead of regular rules for angles and TH, this -4 TH penalty assumes a throw at the roughly 45° angle that the skill specializes in; use an additional -1 TH per 15° higher or lower.
Full-body freedom of motion is vital to these special throws, more so than with a simple knife or axe chuck. Apply the Half modifier penalty for positive encumbrance.
Spinning: Examples of specialized distance skills include Discus Throw and Shotput, with their twirling routines, or the spinning, two-handed Hammer Throw (totally different from the beloved Axe/Mace Throwing). Spinning disallows forward Move during throw. (Limiting effective skill for distance purposes to Speed x 3 is also a nice, advanced touch.)
Javelin Throw: Call the track and field Javelin Throw a specialized distance skill that requires you to run for a full second or more. There's no Javelin Throw skill penalty for throwing on the run i.e., no loss of distance but there is the -4 TH penalty for movement if you try to hit a target on the run, in addition to the -4 or greater TH penalty for specialized distance skills described above.
Example: You're a powerhouse track and field challenger, with ST 15, Speed 7, Move 8, and Javelin Throw-17. Assume a 3-lb. arm mass and a 2-lb. javelin. Can you approach the world record of a 103-yard toss?
Td is the lesser of 15 x 1 x 10 / (3 + 2) = 30, or 7 x 1 x 10 = 70. Use Td 30.
Let's say a great skill roll succeeds by 10 and increases Td by 100%. Add another 30% for All-Out action and, say, 20% for Extra Effort. That's a 150% bonus, taking Td from 30 to 75.
That's your base distance in yards with a long throw. Of course, you throw at a fast run: add twice Move to distance, for a toss of 91 yards. Good enough for the bronze, maybe.
You can toss a baseball with Throwing or Grenade/Rock Throwing, but the scientific wind-up and release of a pro's pitch is a unique animal.
Make Pitching a separate Hard throwing skill, and let it add lots to throwing speed. Boost Td by 20% (!) per level over 10, and raise the Td bonus from All-Out action to 50%. Also let that explosive Step count as added full Move. (That adds Move x 2 to distance, per the above rules for distance bonus from Move.)
The difficulty of mastering a blazing hurl isn't its only drawback. You need to Step and throw, after taking a full second to "wind up". (GMs with a bent for mental play may require a Will roll to get that enhanced All-Out action bonus.) Like other specialized distance skills, Pitching is affected by encumbrance. Unlike those skills, though, a pitch suffers no penalties for aiming at targets, or for flat (up to 15°) throws. Rather, apply a full -4 skill penalty to throws made at greater angles, in addition to normal TH penalties for angle.
But if you've got the time to prepare and the accuracy to make a head shot, Pitching can be a deadly combat skill! Baseball-loving GMs can also create Hard maneuvers of Pitching for sliders, curveballs, fastballs, and so on. As an example, the Fastball maneuver might default to Pitching -4, but boost the Td bonus to 25% per skill level.
Example: How do you throw a 100 mph fastball? Start with phenomenal stats: a ST 16 arm, Speed 7, and Fastball-20. Td is the lower of 16 x 1 x 10 / (3 + 1) = 40, or 7 x 1 x 10 = 70. Use Td 40.
Now add a 250% Td bonus for a great Fastball roll that succeeds by 10, and 50% for All-Out action, increasing Td by 300% to 160.
If you want to know how far that ball goes, start with your Td of 160, and halve it for a flat throw: 80 yards. Now add twice your Move: total 94 yards.
If you want to know how fast that ball travels, see the calculation for Ts below. Your Ts is 40; add your Move to that to get 47 yards per second, or 94 mph. Keep working at it!
You can invent specialized maneuvers for throwing skills. One of the most likely would be Range, a Hard maneuver that adds to skill for purposes of Td bonus only. Limit the maneuver to Skill +4. It's useful for building world-class distance throwers or baseball pitchers with more speed than accuracy.
As mentioned earlier, Indirect Fire could also be a Hard maneuver to reduce the TH penalty for high-angle throws.
Most throwing skills are used one-handed. The above sports throwing skills are all exclusively one-handed (Pitching) or two-handed (Hammer Throw).
It's up to you whether the general Throwing skill allows its bonuses when used two-handed, or whether a separate Two-handed Throwing skill (cross-defaulting to Throwing at -3) is needed. The latter is more realistic.
Either way, take the version you prefer, add some individual skills like Caber Tossing, and you're off to the Highland Games.
You can compute throwing speed upon release, Ts, as the square root of (Td x 10). Ts is in yards per second. Multiply by 2 for mph.
Forward movement when throwing also adds a speed vector, in the direction of movement. If you throw at a flat angle, Move in yards adds directly to Ts.
Clever players with a burning need to know the flight time of a spear can borrow notes from the jumping rules' Hang Time section. For a throw with a max height of 5 yards (ignoring starting height), this will be a second going up and a second going down, or two seconds total. A throw with a max height of 20 yards will spend a whole four seconds in flight. (It's useful to remember that max height for a 45° throw is one-fourth distance.)
Of course, most GMs will play all thrown attacks as instantaneous, for simplicity. Playing out real flight times puts strange "time delay" attacks into combats but that is how missiles work!
Even if an incoming attack does have a long flight time, you won't necessarily get a big bonus to Dodge it, as you won't know until the last instant exactly where it's going to hit. But you can certainly use the spare time to run for cover, or to wisely choose All-Out Defense just before the missile lands.
Throwing speed is unchanged by gravity (you still accelerate the same mass), but the distance your spear travels will vary greatly. Divide all distances by local gravity.
In zero-g you can hurl an object with a Move equal to Ts which will travel forever unless something stops it. Even in gravity, a Ts greater than the local planetoid's escape velocity lets you launch satellites.
If skill, All-Out action, running, and other factors increase the speed and distance of a throw, shouldn't they also increase the force of impact? Absolutely! Ignore this for simplicity, or read on:
Increases in Ts, not Td, should convert to proportionate damage bonuses, for consistency with collision rules presented in Book 6. A 50% bonus on Td (i.e., Td x 1.5) converts to a (square root of 1.5) damage multiple. A 100% bonus on Td (i.e., Td x 2) converts to a (square root of 2) multiplier.
For moderate Td bonuses (100% or less), here's a safe fudge that avoids square roots: Use half the Td bonus as a damage bonus. A 20% Td bonus is a 10% damage bonus; a 50% Td bonus is a 25% damage bonus. Round up for fun.
Forward movement isn't treated as a Td bonus and thus is harder to work with. For simplicity, treat significant Move as a 40% Td bonus if a flat throw, 20% otherwise, and ignore completely if Move isn't significant (GM call).
These rules result in pretty moderate damage bonuses, but spear-chucking PCs should be pleased.
Example: Spear Throwing-16 equates to a 30% Td bonus, or roughly a 15% damage bonus. That's good for +1 damage per 6 or 7 points rolled.
Example: And that major-leaguer from the pitching rules earlier? With a ST 16 arm, his pitch (say, thr-2 damage for a hardball) is already injurious. With a Td bonus of 340% from Fastball skill, All-Out action, and forward movement, he'll get a damage bonus of 110% (square root of 4.4 = 2.1). Ouch! Do the math: with a brain shot, this pitch can kill!
These rules give good results for all throws, whether for average humans, Olympic-level athletes, or non-human creatures. Note that some numbers will differ: for example, calculated distance for an average human throwing a rock or similar small weight will be lower than under GURPS rules. That's fine, as GULLIVER offers many ways to boost that distance: movement, skill (not just Throwing skill), Extra Effort, and the realistic All-Out throw.
Throwing's hard with heavy stuff. When you spend power to support and balance a load, the amount left over for throwing drops drastically:For every full (maximum lift/10) pounds of object weight, reduce Td using the progression x4/5, x2/3, x3/5, x1/2, x2/5, x1/3, x1/4, x1/5, x1/10, x0.
This rule is a nice addition to the throwing mix, really setting one-handed and two-handed throwing apart: an additional distance penalty every 6 lbs. vs every 25 lbs., for the average human.
That's a lot more realistic once weight gets above a few pounds, but the rule's labeled advanced because of the extra complication. Then again, the PCs probably won't often throw things that are heavy enough to bring the rule into play. Use or ignore as you like.
Adding twice your Move to distance is a simplification. A correct addition multiplies the missile's air time (twice the time required to fall from height of throw) by your forward Move. Remember that height is one-fourth distance in a 45° throw.
Boosting distance by (Move x 0.9 x square root of throw height), where Move and height are in yards, gives a good approximation.
Unlike jumps, your throws start from a distance above the ground. This boosts distance, but working the factor into the calculations is not at all fun. Here's a fudge:
Throws have a starting height of your height for overhand throws, half your height for underhand (including most two-handed) throws. Adjust for nonhuman position, unusual throws, etc. Throwing from a raised platform also counts as starting height.
This starting height adds directly to the maximum height achieved by a throw. It also increases distance by 50% or by starting height, whichever is less.
Example: If you care about the detail, your axe toss has a starting height equal to your two-yard height. Add two yards to the maximum height of its trajectory, and increase distance by 50% or by two yards, whichever is less.
As with jumping, you can use a precise measure of limb length rather than simple Linear Scale. But it'll probably be interesting only in your Megalos vs Caithness: The Knights of Track and Field campaign.
This is important for thrown objects, but isn't easy to play with. Best to ignore it.
If you just have to do it, guess at an ftv from the Appendix below, and adjust Ts in the same way as Js. Ignore ftv and drag for aerodynamic weapons (or do some research and locate actual frontal surface area for a javelin). Very small rocks will have lousy ftv and won't fly far, regardless of who throws them.
The Throwing Art skill mystically ignores air resistance. "Yes, Inspector, a potato chip right through his neck!"
Below is a look at what makes up your Dodge stat. (Details of using your Dodge, including effects of relative target and attacker size, are covered in Book 5.)
Start by fixing an odd quirk in GURPS. Go to p. 77 of the Basic Set, toward the bottom of the page. Find the sentence "This 'active defense' is equal to your Move". Change it to read "This 'active defense' is equal to your Speed, rounded down."
Dodge does not equal Move in GURPS, even if the Basic Set hasn't noticed. While both stats are based on Speed and adjusted for encumbrance, that's where the similarity ends. Enhanced Move, Super Running, Combat Reflexes, Flight, Enhanced Dodge, Boxing, Running, and many more traits affect Move but not Dodge, or vice-versa.
Move is an "extrinsic" number that varies with unit of measurement; Move 5 (in yards) is also Move 15 (in feet), with either measurement equally valid. Dodge, on the other hand, is "intrinsic" and can't be measured in units.
The correct calculation for Dodge is as follows:
Size, Running skill, and Enhanced/Reduced Move do not affect Dodge!
With the above, there's no reason to use GURPS' special rules for animals' Dodge scores. In an anything-goes game like GURPS, who's to decide what does and doesn't qualify as "animal" to begin with?
The special rules appear to have been created as a fix for widely varying animal Move scores that don't always translate into reasonable Dodge scores. But that's a fix for a problem that shouldn't exist if you correctly base Dodge on Basic Speed, not on Move, the problem is gone. Use Dodge = Basic Speed for humans, animals, or any creature.
Unfortunately, the Basic Set animal descriptions don't include Basic Speed; what's listed there as Speed is, confusingly, actually Move. That means you have to compute actual Basic Speed on your own from HT and DX, or make up something appropriate: Speed 7 for a fast predator, Speed 3 for a lazy herbivore, etc.
The were stats from CI p. 44 also mistakenly use Speed to mean Move. Fix this by using the character's own computed Speed for the were's Speed, and the listed stat for Move.
Modifications to a creature's Move from its size and shape won't affect Dodge. Add 1 to Dodge for Combat Reflexes for alert critters, and adjust for natural encumbrance if you're getting that detailed with animal stats.
But the most important rule is don't sweat it. Any reasonable, off-the-cuff Dodge scores, even those from Basic Set and Bestiary descriptions, are fine for NPC animals.
Appropriate Dodge for different body areas deserves a closer look. Appendages presumably retain better mobility than the overall body despite encumbrance; GURPS applies no TH or Parry penalties to an encumbered fighter's sword arm. Likewise, an arm, wing, head, striker, or tail can probably avoid attacks more easily than a whole body can.
Strict realism would have you computing "encumbrance" and Dodge separately for each appendage based on its weight and its portion of overall ST, but here realism is too obnoxious for its own good. Something simpler:
Let free-moving appendages suffer only half normal Dodge penalties from positive encumbrance (round down).
If you have None or better encumbrance, a targeted appendage gains a +1 to Dodge an attack!
Legs work differently. A leg supporting your weight has no improved mobility, and takes the same Dodge as the body. An exception might be a flying creature, whose dangling legs could nimbly draw up out of the way of an attack.
Example: A loaded-down PC with Light encumbrance has a -1 Dodge penalty vs a torso attack, but no penalty vs an attack on her arm or sword. An elephant with Extra-Heavy encumbrance has a -4 to Dodge attacks against the body, but only -2 to Dodge an attack against its trunk. A Super with Neg. 4 encumbrance has +2 Dodge versus any attacks, and an extra +1 to Dodge attacks against appendages.
Head: Your head has an additional advantage: eyes. An attack directed at your face is as "visible" as it could possibly be, and you benefit from an instinctive flinch reaction.
If you like that effect, add +1 to Dodge an attack against an appendage that has eyes (the head for humans, but not necessarily for other races). The appendage must be mobile (on a neck, or otherwise more mobile than the whole body) to gain the bonus, and the attack must be coming from your field of vision (a "front" vision hex).
Combined with the general Dodge bonus for appendages described above, that's a +2 or better improvement on rolls to duck beneath a swipe at your noggin. Jot it down if you're apt to forget; it's an important modifier in a boxing match or barroom brawl.
Position: Sitting or kneeling gives you a flat -2 AD in GURPS, but GULLIVER suggests the following modification:
Either position gives you a hefty -4 to Dodge attacks against your lower body or legs. The upper body (i.e., general torso) takes the -2 GURPS penalty, and mobile appendages halve that to -1.
Parries and Blocks while sitting or kneeling use the overall -2 AD penalty.
Just because there's no real-life name for a skill doesn't mean it doesn't exist! There may be no School of Dodging out there, but the Boxing skill includes related instruction, and any experienced fighter will have learned to duck and weave. An axe-wielding warrior who defends by dodging should become more proficient at the move than a sword fighter who parries nearly every blow. And who's to say that Dodging, under that very name, isn't an honored skill taught to the warrior elite on Altair 12.
Many GURPS players have introduced a Dodging skill to their games; the question is how to best do it.
One method is to figure Dodge as Dodging skill/2, like a weapon skill parry. The drawback: very high Dodge scores for a high DX and a little skill.
Another method: let Dodging work like Running, adding skill/8 to Dodge. That's perhaps an improvement, but see the notes in the Appendix on letting Running skill add to Move vs letting the skill replace HT in the Base Move equation.
For the same reasons given there, the best way to game a Dodging skill is to base it on DX, and let the skill replace DX in the (HT+DX)/4 base for Dodge, rather than having it directly determine or add to Dodge. The skill would also replace DX in Contests when avoiding slams, grapples, etc. Try it: it's fun and useful, yet doesn't allow easy abuse.
Rules for balance are simple. A balance check is a roll against DX, with a few modifiers tacked on. Success means you maintain balance; failure means something bad.
Physical: Modifiers include encumbrance (use the Half modifier) and stability from an innate sense of positioning (GURPS' Perfect Balance advantage), or limbs that act as balancers and points of contact with the ground. Book 3 suggests an Improved Balance advantage costing 2 points per +1 bonus coming from a tail, limbs, or a low center of gravity; bonuses from limbs are the control bonuses discussed earlier.
Ignore bonuses when appropriate: a crippled tail offers no bonus. Halve bonuses that depend on contact with the ground from a low center of gravity, or multiple legs if you're knocked through the air. An innate sense of balance, which always works, is a +50% enhancement.
The Poor Balance trait gives -2/level.
Situational: Use these modifiers:
* Double for a missed blow!
Knockback: Additional situational modifiers following knockback from a weapon, slam, or other collision:
Remember that Move is effectively halved when you're knocked backward; that affects the full Move number!
Rules will state when to make a balance check: after a certain amount of knockback from a blow, for example, or a walk across a narrow beam. If circumstances don't quite warrant a regular balance check (such as minimal knockback from a weak blow, or walking a wider beam), the GM can still require a check at +4.
Further details on balance checks after knockback are in Book 5.
Special checks: If balance is really poor, actions that don't normally require a balance check such as making a normal athletic action may require a check. The mechanism: make a balance check at +10, minus any penalties. If the check needed is 14 or less, go ahead and roll; otherwise, ignore it to save time.
Use this for characters with the Poor Balance trait; with their heavy balance penalties, even a simple combat blow, defense, running, or other athletic action can cause trouble. For really bad cases, check for semi-athletic actions (like walking) at +2, or even just standing there, at +4.
The rule is also the reason failed kicks make you fall: roll vs balance +10, -2 for an attack, doubled to -4 for a miss; and -6 for one leg left standing. In other words, make the classic GURPS balance roll after a missed kick. (Call a successful kick only -2 as the leg returns quickly, -2 for an attack, for a net -4 generally, no check needed.)
You can ignore this balance +10 roll in other situations but it does allow for a clumsy oaf to knock himself down with an ill-conceived and poorly-aimed All-Out swing with a too-heavy weapon. And that's kind of fun.
Simple rules: Failure on a balance roll means you fall.
Detailed rules: Failure by 3+ is a fall; failure by only 1 or 2 means you're off balance.
Various rules appear throughout GURPS books for characters knocked off-balance without falling. Here's a unified rule:
Treat off-balance as 5 levels of Poor Balance: you suffer -5 athletic DX, -2 AD, and -10 balance.
Any athletic action will require a straight balance check (+10 per the "special check" rule above, but -10 for off-balance). Failure by 3+ is a fall, any other result means you remain off-balance. (Critical success moves you into balance.)
Recovery: At the beginning of your next turn you can check for recovery. Make a balance roll as above: +10, but -10 for off-balance, plus any other modifiers. Take a bonus on the roll if you can Step in the direction of your leaning (GM decides direction): +4 if a front movement hex, +2 if a back hex.
If you succeed by 3 or more, you recover and can act normally. If you fail by 3 or more, you fall down. Otherwise, you remain off-balance with all normal effects; try to recover again on your next turn.
A Balancing skill (P/E) would be useful not only for walking tightropes and balance beams, but also for staying upright in the rough-and-tumble of contact sports and combat. It'd help a trained dog walk on its back legs, or a character function with mobility difficulties like Lame.
Let Balancing replace DX in any balance roll. Reasonable defaults would include Acrobatics -2 and Body Sense -2.
Swimmers, fliers, and 0-g spacers that "fall" or are knocked "off-balance" are disoriented. The above rules don't really apply; roll Swimming, Flight, or Free Fall as appropriate to regain control. Fliers need to regain control especially quickly they fall until they do so!
If whatever sent you spinning did so with significant force, you may take a big penalty on the recovery roll. That penalty will disappear after a swimmer's first recovery attempt water halts the spinning but may last for several turns before air slows down a flier's spins. And vacuum won't stop the cartwheeling of a head-over-heels astronaut; the penalty persists, and recovery may take a very long time!
For simplicity, the above rules hand you five levels of Poor Balance to represent the off-balance state. It's easy to turn this into a variable degree of unbalance. Instead of gaining those five levels for failure by 3+ on a balance check, do this:
Balance checks: When making a balance check due to some hazard, take one level of Poor Balance per point of failure: two levels for failing by 2 points, five levels for failing by 5, etc. Poor Balance over 5 levels whether from failure by 6 or more points, or accumulated levels of Poor Balance means you fall.
Of course, whatever your level of Poor Balance, you can attempt to attack or otherwise act normally, but remember that this may force another balance check (at +10, -2 per level of Poor Balance, plus any other modifiers), and another chance to worsen your balance or even fall.
Recovery: Your chance to regain balance occurs at the start of your next turn, per detailed rules. Make a balance check (at +10, -2 per level of Poor Balance, plus any other modifiers, including the bonus for a Step). Every point of failure adds a level of Poor Balance; you fall if levels exceed five. Every point of success removes a level of Poor Balance, moving you toward your normal state.
Results: These advanced rules create fun scenes in which fighters especially those on treacherous surfaces teeter in and out of danger of falling.
In GURPS, any one position change requires one second, or longer if you're encumbered (BS p.103). With negative encumbrance, you could presumably make a position change in less time. A simple suggestion: position changes take half as long at Neg 5 encumbrance.
A more detailed method for the dice-rollers out there: Roll DX+3, and add the Full modifier for encumbrance. Success means a full second is spent making the position change; every 5 full points of success halves the time spent. Failure means two seconds were spent; every additional 5 full points of failure doubles this time.
To make two position changes, roll for the second one as soon as the first is completed, or make just one roll but at an additional -5; the effect is the same either way.
A half-second change lets you go from kneeling to standing in the first half of a second, and act freely in the second half. A quarter-second change can be treated as "zero time" (like a Fast-Draw roll), but two of these would make a half-second change. With the GM's permission, substitute Acrobatics +3 for DX +3 (and remember that a modifier for encumbrance is already figured into Acrobatics skill).
This rule lets small, light creatures change position almost instantly, while big heavy ones struggle to get up. See Book 3 for additional traits which affect the difficulty with which you change position.
Book 3 looks at the stances different creatures take. A human crouching can be considered to be in a low stance. This would be good for a +1 on balance rolls but it's not a normal pose for a human, as the combat and movement penalties attest.
A human kneeling with legs apart could be considered in a Very Low Stance for a +2 balance bonus, though the Move and other penalties are heavy.
Lifting is pretty straightforward in GURPS: you can lift up to Load ST x6 lbs. with one hand, Load ST x 25 lbs. with two. Add 10% to Load ST for each additional arm, up to some reasonable number.
Similar multipliers will determine your performance with bench presses, leg presses, and other weightlifting feats. Players experienced with lifting can take guesses at proper multiples, but there are no obvious numbers unlike PCs' across-the-board ST stat, real people's relative performances can vary wildly with the lift in question.
Extra Effort is a fine way to lift a little more. Another is through proper technique, timing, and balance:
While GULLIVER condemns all skills based on ST as fundamentally broken, the ST-based Lifting skill initially seems to work, thanks to unusual mechanics. Lifting adds 1/10 skill to ST when lifting: a tiny PC with Load ST 1 and skill 1 adds 0.1 to Load ST, or 10%; a huge PC with Load ST 200 and skill 200 adds 20 to Load ST, or 10%.
That initially doesn't look bad, but the mechanics are un-GURPSlike: skill 1 and skill 200 don't fit the usual scheme. Worse, practicing technique enough to increase skill level by one will double the tiny PC's lifting ability, while the huge PC gets an infinitesimal 0.5% boost. In other words, the rule is broken after all.
Improved rule: For more familiar (and workable) mechanics, base the skill on HT or DX, so any character will have skill in the typical 5-to-20 range. For effects of skill, use this:
Increase Load ST in lifts by 5% for every two full levels of skill over 10.
Rolling: You can make the above a roll vs Lifting. Success by 2 or less increases Load ST by 5%, and every additional 2 full levels of success increase Load ST by an additional 5%.
Failure offers no bonus. A critical failure means you strain yourself! (Taking the automatic bonus is far more certain, but rolling is the way to go when shooting for a record lift.)
These rules add enough detail to feats of running, jumping, throwing, and so on that sports contests between PCs and NPCs can be pretty interesting. Be sure to use lots of skill rolls and Extra Effort to wring out peak performance. (For a psychological twist, PCs could even try to "psyche" themselves beforehand with a Will roll; success or failure modifies later Extra Effort rolls. But failure should also subtract a small amount from base performance!) Meanwhile, combat rules from GURPS and Book 5 will come in handy during games like hockey and rugby.
You can even develop simple rules to run any sports match like a combat. Borrowing ideas from MA 2E p. 62, it'd be best to skip over long periods with a few quick skill or other Contests to determine results in abstract fashion. Intersperse these with short periods of turn-by-turn action.
All sports skills would probably take the Half modifier for encumbrance. That doesn't necessarily mean lighter is better. The pushing and tackling of American football, rugby, and the like will benefit a lot from ST and weight, which will overshadow the effects of a little positive or negative encumbrance.
Small size makes you hard to spot. Subtract your Size from Stealth when rolling vs Vision. Range should come into play too, so tiny PCs foes trying to get the drop on each other will have a hard time due to small sizes, but an easy time due to the relatively short ranges involved. If you like, just use the difference in Size as a bonus on the smaller side's Stealth and a penalty on the larger's Stealth.
Hiding places make a big difference too (BS p. 67), and small creatures will have an easier time finding such spots.
Weight is a trickier thing: heavy-footed clomping is bad for stealth, but if you can control the weight, lifting and placing your feet gently, it's not a problem. Apply your Half modifier for encumbrance to Stealth when rolling against a listener's Hearing.
Of course, it's possible that absolute weight might play a role, increasing the chance of snapped twigs, groaning floorboards, etc. no matter how smoothly you move. Apply modifiers to Stealth vs Hearing as appropriate say, -1 per every 10x multiple of human weight, +1 per 10x divisor (up to +5).
These factors make it very easy for tiny PCs to sneak about, but use common sense you'll see even the quietest mouse if it runs directly across your field of vision.
A full listing of Stealth modifiers could include the following:
Movement (vs Vision or Hearing)
- No movement: +5
- MV 1/10 or less: +4
- MV 1/5 or less: +2
- MV 1/2 or less: no modifier
- Up to full MV: -4
- Sprinting: -6
- Not adapted to Environment: -2
Range (vs Vision or Hearing)
- Subtract Range modifier from Stealth
Distraction, target fatigue (vs Vision or Hearing)
- as GM determines.
Size (vs Vision)
- Subtract Size from Stealth
Hiding places, relative to your size (vs Vision)
- Few "natural" hiding places: up to -5, or much worse if directly in field of vision
- Many hiding places: up to +5
Carried items (vs Hearing)
- Leather armor: -1
- Scale, chain armor: -2
- Plate armor: -4
- Stuffed backpacks, treasure sacks, axe-and-sword belts, etc.: -2 or worse
Feet (vs Hearing)
- Hard soles, hooves: -2
- Non-retractable claws: -1
- Soft shoes, bare feet: -0
Surface (vs Hearing)
- Gravel, rocks: -2
- Dry grass, leaves: -4 or more
Listener (vs Hearing)
- vs Dogs: -5
- vs Geese: -1/goose (max -6)
Weight (vs Hearing)
- encumbrance: add Half modifier
- absolute poundage: +1 per x1/10 multiple of human weight (max +5)
- absolute poundage: -1 per x10 multiple of human weight
Skill (vs Hearing)
- Light Walk skill: add skill/5 to Stealth.
All modifiers are cumulative.
Apply the Full modifier for encumbrance to this cinematic skill from Martial Arts. Also apply a modifier for absolute weight: +/-1 per 10x multiple of human weight.
A small shadower might easily escape his target's notice, but at the same time would stand out in the surrounding crowd for the very reason of his odd size. He'd soon be spotted (though possibly after being stepped on). Don't forget too that a tiny shadower needs to be able to keep up with his target.
Any shadower noticeably larger than the surrounding crowd will be very easy to spot: -2 to skill just for being on the tall side of normal, -4 for Gigantism, -8 for size a full Size level larger than the crowd, no chance for height beyond that. Halve those penalties if odd-sized beings are a normal part of the spaceport or fantasy marketplace crowd.
Apply a Tracking modifier equal to half the target's Size. A heavy target is easier to track too: let a target's Half modifier from positive encumbrance act as a bonus on a tracker's skill, while negative encumbrance acts as a penalty.
Absolute weight is important on soft ground: start with no Tracking bonus for soft ground, then use the notes from Stealth above to further modify for the target's weight.
An inch-long PC would be very hard to track (-5 for size, other penalties for weight and negative encumbrance), even for another tiny PC.
There is no modifier for relative size. The tiny character can see details a human would miss, but the latter gets a better "big picture" from above. Likewise, the tiny character could easily spot the bent grass of your footprint, but for him your next footprint would be very far away. So it's just as difficult for small characters to track big ones as it for big characters to track each other.
Throughout all of the above, sometimes your best just isn't enough. GULLIVER suggests the following rules for Extra Effort, which differ from the BS and CII rules:
You need something to roll against, preferably something that represents "grit". Your HT, modified for Will, works fine here.
That's the base roll for everything; there are no rolls against extrinsic stats like ST! Adjusting a stat by rolling against itself is generally a bad idea. Your Cidi PC could never lift that extra six-pack if he has to roll against ST 3, demonstrating a case in which GURPS' Extra Effort rules just don't work. But with HT as the base, the Cidi has the same chance any character has of boosting his efforts by some amount appropriate to his ST.
Make the Extra Effort roll, at -1, -2, or more for each level of desired extra effect.
Extra Effort with movement requires you to first maintain sprint speed!
Extra effect will vary with the situation. In general, it should represent some extra percentage of any stat measurable in units (lifting power, running speed, throwing distance etc.).
To boost abstract stats, extra effect measured in absolute numbers is fine. For example, you might make an Extra Effort roll to boost Dodge, at -2 for each +1 Dodge. The examples below also allow an Extra Effort skill bonus for generic athletic skills, which could be useful when you roll against a skill in a Contest, make a control roll, etc.
Extra Effort costs a point of fatigue whether it succeeds or fails. (A critical success costs nothing.) GMs with a bent for more psychological play can let Extra Effort subtract a point of Will too, to be regained only by rest, confidence-building measures, or success at some task that's meaningful to the character. A PC with Will reduced to half or less might be unable to attempt any more Extra Effort (and suffer -1 on normal efforts).
Extra Effort might also subtract from the original effort, in coordination if not effect. For example, a javelin hurled with Extra Effort may fly far but won't likely enjoy pinpoint accuracy. A -1 on coordination (TH for combat skills; control rolls for skills like Jumping) for each level of extra effect works. But it's up to the GM whether to apply this always, apply it only to Extra Effort failures, or ignore it.
Critical misses also introduce danger to Extra Effort. The examples below suggest one or more critical miss dangers for each use of Extra Effort; the GM can select from among those, or invent new ones.
The Table below offers suggestions. Penalty refers to the Extra Effort roll penalty for each level of desired extra effect. Penalty is generally low for slow tasks like lifting, high for quick ones like jumping.
+10% Load ST
sprain, fall, wild throw
sprain, fall, drop item
generic athletic skills
Below are notes on fine-tuning rules for miscellaneous other feats, most of which aren't what you'd consider athletic. Physical properties size, strength, weight can still affect use of the abilities:
Small creatures seem to have lots of Manual Dexterity in their nimble fingers, and big creatures the opposite, but much of the effect will come simply from relative size, not coordination. Decide the base Size that a job is suited to, and apply modifiers for relative Size.
For example, a delicate lock made by Size -1 Halfling hands would carry a -1 penalty for a Size 0 human picklock, a -2 for a Size +1 Ogre (who could maybe just snap the little thing off anyway), and so on. Beings smaller than Halflings will receive size bonuses but up to a limit of only +2 or so, as the GM decides. Lock picking never becomes automatic just because you're tiny.
A character needs to be noticeable for this advantage to work. If the GM rules that a 500-lb. horse isn't impressed by the charisma of a one-ounce PC, then so be it. As a rule of thumb, halve the reaction bonus if the animal is 3 to 5 Size levels larger, and ignore the bonus if bigger than that. (Add a Size level to those for the more expensive Beast-Kin advantage.) This will limit the effects of a thumb-sized PC's Animal Empathy to cats and small dogs.
Just as Riding and Teamster require different skills for different types of animal, so might Animal Handling. GURPS Old West takes this approach. It's unlikely that a dog trainer would know how to care for cattle, or that a cowboy could herd crocodiles.
If you game Animal Handling this way, required specializations might include:
Further enhance the skill with the usual mechanics:
Tiny PCs: The last few required specializations above, dealing with smaller animals, could be learned by tiny PCs. As with the Animal Empathy advantage, animals much larger will tend to ignore (or eat) PCs. Add an Animal Handling penalty equal to every level of Size difference over 3 between the animal and the handler.
Remember that low-IQ animals are basically untrainable, and can not react in a "friendly" way like a dog or horse might. Animal Handling (Arthropods) won't let your tiny PC befriend or train a spider, but might let him get by the arachnid without provoking or frightening it.
In a fantasy game, Animal Handling and Riding will let tiny PCs train and ride insects, crows, whatever.
Falconry: Change Falconry to an optional specialization of the required specialization Birds.
A skilled falconer would be a deadly enemy in a game of tiny PCs. "Parakeetry" or "Pigeonry" are other possibilities, although these birds won't bring home dinner.
It can be hard to control an animal if you're far smaller than it. As a rule of thumb, reduce Riding skill by 1 for every full 3 levels of Size difference between you and a big mount At some point, the animal will ignore you or simply shake the nuisance off its back.
Whether you need to use force to steer the beast, or just make it clear that you're back there giving the orders, depends on the animal. A docile elephant might take orders from even the tiniest character with no Riding penalty, as long as the rider is big enough to be felt and heard. Wild or excited animals might respond to force only; substitute a 10x difference in Load ST for 3 levels of Size in the rule of thumb above.
No special rules are needed for characters who are too big for their mounts if the animal's flat on the ground, you're not going anywhere.
In general, social skills will work the same at any size, assuming you're not so small that your listeners cannot see or hear you. But size and power do command attention.
Although a strong arm can say a lot, no social skill should be based on ST, whether normally or by default. Relative ST means a lot, while absolute ST means nothing. Taking Leadership as an example, there's no reason why the members of a community of Giants should all consider one another gifted leaders!
Here's a suggestion for bonuses on Intimidation, a perfect example of a social skill affected by relative power:
Always base the skill on IQ, not ST. Adjust for Strong/Weak Will.
Add +1 per 6" of height the intimidator has over the target (or the equivalent of 6", as seen from the target's size), up to a maximum of +4. Beyond that, simply add +1 per level of Size difference.
Apply a -1 if the intimidator is shorter than the target, or -2 if over 6" shorter (or the equivalent, as seen from the target's size); beyond that, subtract 1 per level of Size difference.
Displays of ST can also add to skill: apply a bonus of from +1 to +5 for superior ST of up to double that of the subject's, and an additional +2 per doubling of ST thereafter.
Intimidation can affect up to 25 people of similar size. Multiply this number by the difference in Linear Scale (minimum one target). You could intimidate hundreds of 2" Micro humans, just as Godzilla sends all of Tokyo running.
Leadership should always be based on IQ with bonuses for Will, Charisma, and other social traits. Relative power might use the same rules as Intimidation above, in a setting that values physical power highly in the pecking order. That might be the case for a warrior society, which would allow even more bonuses for Reputation and perceived fighting prowess.
A modern-day setting might place far more importance on intelligence and skill in leaders, halving the above physical power modifiers. Until the corporate jet crash-lands on a small island, that is, and rule of the strongest takes over among the survivors.
Whether Intimidation-style power bonuses apply depends upon the interrogation are we talking prying conversation, or out-and-out torture? Whatever the situation, a modifier of at least the difference in Size between the questioner and target makes sense. That makes things tough for a tiny interrogator but if you can think of some way to browbeat a much bigger target, more power to you!
Impersonating someone of a different Size is normally impossible, but could be done on television with scaled props.
This is hard if your victim is small: subtract your Size difference if the victim is unaware. If he is aware of your presence, the GM can apply big penalties or rule the feat impossible a Giant in a medieval market cannot casually walk up to people unnoticed and start emptying purses! (Besides, it's so much easier to just turn them upside down and shake the good stuff out.)
If you're smaller than your target, there is not necessarily a bonus unless the GM allows one you'll have to make awkward reaches, actually climb up on sleeping targets, and so on.
This may be tiny PCs' only real weapon against big enemies. To preserve game balance, normal use of the skill should create a dose of poison appropriate to the character's size; making a dose to affect something much bigger should require a lot of work and possibly skill penalties. The same applies to uses of the Alchemy skill.
Obviously, a big creature can hide bigger things than a small creature can. Use Size modifiers: an 8" Cidi will have a lousy Holdout skill (-6 penalty), but a Cidi-scale handgun would be good for a +6 bonus.
The GM can apply penalties for those operating vehicles designed for bodies of a different size, such as -3 for one Size level larger or smaller, -6 for two, no normal vehicle operation possible thereafter. (Players will dream up abnormal solutions, of course.)
A cramped space like a jet cabin will carry even more severe penalties: -2 simply for being on the tall side of normal, -4 for Gigantism, -8 for one Size level larger, and nothing possible for those bigger. Reduce all penalties by 3 for Double-Jointed, by 5 for Flexibility.
A spaceship, on the other hand, might be controlled with an electronic panel, carrying smaller penalties for size, or controlled by voice, carrying perhaps no penalties.
The solution, of course, is to ride an appropriately scaled vehicle. Little cars will handle differently from the full-sized thing, though, so size travelers will have familiarity penalties.
Physical size and the use of magic, psionic and martial arts abilities is a topic in itself. See Book 8.
Substituting skills for attributes is a common GURPS mechanic in many situations, including combat: a skill like Judo can replace many DX rolls.
But it usually makes sense to have a skill replace only the attribute that it's based on! Letting an IQ-based skill replace DX, or a DX-based skill replace ST, often leads to 'broken' situations.
You can use substitutions as an alternate way of handling skills that add to a computed stat, as Running skill does to Move. Instead of adding some fraction of skill directly to the stat, replace a base attribute with an appropriate skill that's based on that attribute.
Running is based on HT, so let the skill replace HT in the (DX+HT)/4 equation when determining the base for your running Move (but not Basic Speed itself). If you have DX 12, HT 12, and Running 14, you have a Move calculated from a base of (12+14)/4 = 6.5.
Consider the advantages. Currently, most human PCs can gain a hefty +1 or better bonus to Move by putting a mere half-point into Running. Yet the cost for additional points of Move quickly tops out at a huge 64 points per +1 Move (i.e., the cost to buy eight levels of Running) a cost right up there with devastating superpowers.
But by substituting Running for HT, getting that first +1 Move will take at least a few points, and the cost of an additional +1 Move tops out at a more reasonable 32 points (as four levels of Running will do the trick).
The method also avoids the double-counting of attributes in a Move score.
For compatibility, GULLIVER examples stick with the traditional use of Running and its friends, but the above option is an improvement. Give it a try.
Top speed, especially for flight and swimming, is the point at which your acceleration is canceled out by deceleration from drag. That's not fun to calculate, though, so GULLIVER sticks to more familiar movement rules. But you can, if you want, incorporate drag effects to a degree into flight and swimming speeds.
Drag is a function of the surface area you present to the surrounding air or water and the medium's density. Drag also increases with the square of any increase in velocity; it's negligible when you're moving slowly, a bear when you want to go fast.
The below looks at two terminal velocities. One is for your velocity in a spread-eagled "flat" pose. That's what parachuters do to slow their free falls, and it's what's relevant to the speed at which a gliding bird descends. Call this simply "tv".
The other is your velocity in the headfirst, "forward" direction. This is a more streamlined pose that presents less surface area and drag. Call this "ftv" ("forward terminal velocity").
Terminal velocity (tv) is the falling speed at which drag from your movement through air offsets acceleration from gravity. It's as fast as you go when falling.
Base: Start with a base 100 mph (Move 50 in yards) in air. Multiply this by the square root of your MAR.
Your MAR is your mass-to-area ratio, and equals Linear Scale as a simple default. See the Appendix of Book 1 for more detailed calculations, including the effects of wings.
Weight: Multiply the result by the square root of local gravity. (Or just start out using WAR instead of MAR; that'll give the same result.)
Air density: Divide by the square root of local air density, with 1.0 being "normal" air density at or near sea level.
Result: The result is your tv in a spread-eagled pose that maximizes drag. It's 100 mph for generic humans, more for large or dense creatures, less for small creatures or those with lots of surface area from wings and other features.
Diving: You can increase tv by diving in a pose that minimizes area and drag usually, the "forward" pose that a bird or superhuman uses to fly. Call this "diving tv", or dtv. Compute it as tv, but using reduced area in your streamlined direction, per the ftv rules below.
For creatures with humanlike forms, dtv roughly equals tv x 1.5, or 150 mph for a human.
Limp pose: Tv computed so far is for a flat, parachuter's pose. If you're unconscious or otherwise limp, you'll fall faster. Set this tv between "flat" tv and intentional "diving" tv. For a human, that's roughly tv x 1.25, or 125 mph.
Water: Terminal velocity in water sinking speed works as above, but water is 800 times denser than air. Divide tv by 30 (roughly the square root of 800). Also remember that weight will differ under water. It can be zero, in which case your WAR is zero, and you don't sink. Weight can even be negative; treat your negative WAR as normal WAR, but your tv represents the velocity at which you float upward.
You can use a number similar to tv to represent the effects of drag on your forward flight. Compute this "forward tv", or ftv, as you did for tv, but with some differences:
Base: Start with a base 20 mph (Move 10 in yards) in air. Multiply this by the square root of your MAR.
Swimmers or fliers will use area in the streamlined "forward" position; a running human, the "flat" position.
Weight: You don't need to use WAR, or otherwise consider weight, gravity, and density; they don't matter here.
Air density and water: As with tv, adjust for air density and water.
Result: Ftv is not a maximum speed. You can go faster if you're powerful enough. In fact, "forward terminal velocity" is a thoroughly bogus term; there's no balance between gravity and drag going on. It's a made-up number which, compared with Move, suggests how forcefully air or water is trying to hold you back.
That was all the ugly part. Now you can do this:
Compare Move and ftv, using the same units (yards/sec or mph). Going faster than a Move of ftv is difficult: average ftv and the Move you thought you'd get; that's your new Move. Buy enough Reduced Move to approximate the reduction.
In general, you won't be slowed unless you're a fast flier or a very fast runner. But swimmers have to deal with a much lower ftv; a humanlike creature will have a tough time topping a mere few mph. That's why nature invented streamlining!
The faster Move is compared to ftv, the faster you decelerate if you turn off the thrust. Again, numbers are left to the daring, but turning off the power at a Move faster than ftv will decelerate you really fast.
With only gravity providing forward thrust, assume Move will quickly drop to ftv; that sets a maximum Move for gliders.
Advanced rule: Forget all earlier rules for setting gliding Move. Simply set gliding Move to ftv.
If you really like, you can figure the reduction on a Super's (or flea's) jump from drag. Adjust Js in the same way as Move. New Jd is (Js squared) /10. Buy Reduced Jump to approximate the reduction in Jd.
Every swimmer knows surface swimming is slower than staying underwater; few animals swim this way. The problem involves the interaction of the swimmer with the propagation of surface waves and is size-dependent, but the physics are too unpleasant to mess with here. As a cheap fudge, multiply Move for any surface swimmer by x2/3 if Move is greater than linear dimension, by x9/10 if not.
A more accurate game approximation for the morbidly persistent: Surface speed (in yards per second) greater than twice the square root of your Linear Dimension is hard to achieve; treat this as ftv and use the rule above. Instead of adding Reduced Move, this effect is automatic if you don't like it, don't swim on the surface!
The physics work differently for creatures under an inch long; ignore the effect.
Notes on the Speed-based equations that limit Jd and Td in jumping and throwing calculations:
Note that Load ST/mass in the first equation for Jd is the same as 1/MSR. This is the acceleration coming from power acting on mass.
Astute readers will also note something interesting in the first equation. Take normal human ST and weight stats, and scale things up or down realistically. Regardless of the creature's size, everything jumps about the same basic distance!
Is this right? Yes, it's an interesting phenomenon that even Galileo noted. Load ST/mass represents the acceleration of the creature, and Linear Scale the distance over which acceleration occurs. The former will generally be the inverse of the latter (barring great interspecies differences), leaving all creatures with similar takeoff speeds and distances.
But it's obvious that most small creatures mice, lizards, even most insects don't make eight-foot broad jumps. They're hit by a limitation: no matter how good that theoretical acceleration from power and mass gets, muscle just can't contract beyond a certain speed! That's what the second Jd equation is for: it sets a maximum acceleration and velocity on your muscle-powered jumps.
Champion jumpers of the tiny world get around this by not relying on muscle, and employing high-acceleration mechanisms like spring-loaded pads of resilin. In game terms, this lets them use the better of the above two Jd formulae, gaining back the jumping ability of big creatures. (Pay 10 points to purchase this technology; see Book 3.) A comparison of humans with locusts, click beetles and fleas shows takeoff speeds and jump heights all in the same ballpark, despite a 100-million-plus range in body weights.
Example: A flea is about Size -17, or Linear Scale x1/700. Without going precisely into stats, assume a WSR that's 700 times better than human, or 15/700. Speed is 7.
Without any enhancements, Jd should be the lower of 700/15 x 1/700 x 15 = 1, or 7 x 1/700 = 0.01. Not much question as to which is lower and indeed, it's said that a flea couldn't jump if it had to rely on muscle-powered acceleration over its tiny leg length.
That's why a flea uses resilin springs instead, letting it take the better of the two formulae: Jd = 1. Takeoff speeds are in line with human speeds, and so are theoretical distances.
But add in the complication of air resistance, and speed in travel will rapidly fall. The above Jd of 1 equates to Js of 3.2. The Appendix crudely estimates ftv = (10 y/sec x the square root of (1/700)) = 0.38 yards/sec. Average Js 3.2 and ftv to get Js of 1.8.
Js of 1.8 gives the flea Jd of 0.32 and a high jump of almost 6 inches. (By comparison, one university study measured fleas at a takeoff speed of 1.9 meters/sec, with a jump height of 8 inches. Good enough!)
As with jumping, the second Td equation is a guess at a maximum speed of muscle contraction. It will usually only come into play for very small creatures.
You could allow a 10-point advantage that lets creatures use non-muscle acceleration to defeat the problems caused by tiny size. Such an enhanced thrower gets to use the greater of the Td calculations.