COSH v2.2

Combat Skill Hack (COSH) for GURPS

COSH v2.2 (2004.01.04) | Copyright 2004 T.Bone tbone@gamesdiner.com | T.Bone's GURPS Diner

All rights reserved. GURPS is a trademark of Steve Jackson Games, Inc. Copyrighted material appears courtesy of Steve Jackson Games.

Created 03/03/14

v2.2 update (04/01/04): Added Peasant's Pike

v2.1 update (03/07/21): Clarified that Offensive or Defensive Grappling only requires Offensive or Defensive Off-Hand Use, respectively. Added new skills: Evade, Batto Jutsu, and Tackling and Blocking. Made some changes to Shield, including addition of new variant. Cleaned up Net skill, fixed many other typos. Added note on Light Weapon under Optional Stuff.

v2.0 update (03/07/13): v2.0 sees COSH taken out of the GLAIVE page and given a page of its own. Other big changes: Revised handling of wrestling-type skills; added new enhancements and limitations; set a new limit on the value of certain combined limitations; added notes on choosing maneuvers; added new skills (including Aikido and Sumo Wrestling!).

v1.3 update (03/04/28): Added new skill from Tail Kinker. Thanks!

v1.2 update (03/04/23): Dropped the beta designation. Clarified use of limits on Dodge Bonus and ST Bonus enhancements. Added example of using COSH to morph a skill into a different skill during play. Added lots of COSH stuff contributed by D. Weber: notes under Other Stuff on using COSH with maneuverless "classic" combat skills, a bunch of new skills, and new "Large/Small ST Bonus (single use)" enhancements. Thanks, D.W.!

v1.1b update (03/03/15): Simplified COSH construction of missile skills, thanks to J. Schipper.

New in v2.0: COSH is so fun, I gave it its own page for v2.0. If you're coming from a previous version, there are several small changes, and one larger one. Previous versions of COSH did not award any limitations to wrestling-type skills for their lack of punches and kicks. This version properly awards them a No Blows limitation; to balance costs, the old Combat DX Rolls enhancement is replaced with more detailed enhancements for wrestling-type stuff. The result is little change in difficulty for wrestling-style skills, but a properly higher difficulty for skills combining wrestling and striking capabilities.

Building Skills

So you want to make a skill that combines one-handed javelin thrusts with a Fencing-like extra Parry and a Boxing-like Dodge bonus. Is the result Easy, Average, Hard, or just plain a bad idea?

ESCARGO already looks at this, in technically-wondrous rules that could literally build any combat skill from the ground up, based on a precise accounting of all component abilities and maneuvers. Could, that is, if the idea were carried out to completion. As explained there, it's a harder task than it appears – and on top of that, the job requires ESCARGO's odd take on skill costs to begin with.

Below is a purely GURPS-like way to build most any fighting skill and set its difficulty. The Combat Skill Hack (COSH) is a nifty kit for designing or modifying any combat skill – sort of a mini- ESCARGO. But COSH is not a theoretical set of tools or a game-wracking new way to play. Any GM can drop COSH into a GURPS game and be designing unique new combat skills within minutes.

COSH began as a simple idea for adding or "swapping" abilities inherent in a skill – say, adding an improved Parry to a skill and making it harder, or balancing that improved Parry with difficulties fighting encumbered. And so on. The core mechanic is kindergarten-level addition and subtraction.

Yes, COSH grew a little in the telling – while it's not hard to make up a list of swappable combat skill features, it is hard to make that list churn out proper difficulty levels for existing GURPS skills. But the finished system remains simple and fun.

How COSH Works

What a skill starts with

Skills start as Average, are either armed (melee, not ranged), unarmed, or ranged, and include the following capabilities or attributes:

What you can add to or subtract from a skill

COSH offers a list of additional attributes, labeled enhancements and limitations. Each has a difficulty rating attached to it, such as +1 or -2. (Most are integers for simplicity, but there are half-point exceptions to assist with the more unusual skills.)

This rating represents added or lessened difficulty. Each +/-1 equates to one additional level of skill difficulty or ease. A +1 enhancement is some factor that makes the skill one level harder: it'd turn an Easy skill into Average. A -2 limitation is a factor that makes a skill two levels easier: it'd turn a Hard skill into Easy.

Here's what you do

1) Note the enhancements and limitations you want to add to a skill, and total up their difficulty ratings. A +2 enhancement, a +1 enhancement, and four -1 limitations would add up to -1, for example.

2) Look at your final difficulty rating. If it's zero, your skill remains Average. If it's -1, your skill is Easy. If it's +1, your skill is Hard.

Example: You build a skill for a new type of weapon. You start with the above list of generic capabilities, then add a +2 enhancement and a -1 limitation. The final difficulty rating is +1. It's a Hard skill.

Simple!

Notes Before You Start

Adding things up

When designing a skill, choose enhancements and limitations that add up to -1, 0, or +1. Saying "I end up with a +6 on my Elvish Whappersmacker skill; I guess we round that off to Hard, right?" will not earn you good will from the GM.

If a skill ends up dangling a spare half level, add or subtract something to get an integer. If you insist on keeping it as is, round difficulty up: a final difficulty rating of +1/2 becomes Hard, just like a +1. That's an ineffective way to design skills!

This system takes great pains to accommodate the existing difficulty levels of existing skills. But GURPS skills were not built according to a system, and these rules can't match every skill perfectly. If you're trying to fit existing skills into COSH, you'll find a few that end up different from their GURPS difficulty level, or even have extreme difficulty ratings outside the -1 to +1 range.

When you can't get a skill to fit between -1 and +1, you can do one of four things:

a) Forget balance; go ahead and round an extreme difficulty level off to Easy or Hard. That's defeating the purpose of these rules, though!

b) Say "bad skill!" and force the skill to fit. Add and subtract enhancements and limitations until the skill falls within the range of Easy, Average, or Hard. That's the right way to use COSH.

c) If you're trying to cram way too much into one skill, design two skills instead. Yes, you can mix abilities from Karate and Judo into one handy skill, but only by compromising; you'll want two or more proper skills to build a truly versatile fighter. Don't shortchange yourself on needed abilities just to be cheap!

d) See Optional Stuff below for more fun things you can do with extreme difficulty levels.

Think skill, not weapon

The listed enhancements and limitations are features of the skill itself, not a special effect of the weapon. A knife's -1 to Parry stems from its small size, not a limitation in Knife skill. But a whip crack really requires training to master; call that an effect of the wielder's training, requiring an enhancement to the skill.

A whip's ability to wrap, or a net's ability to engulf, is also inherent in its construction, not a separate ability granted primarily by skill. But weapon flexibility is treated as an enhancement all the same – not because it adds the ability to wrap or entangle, but because it makes the weapon more difficult to control, and thus makes the skill more difficult.

Maneuvers and skill difficulty

COSH takes number of maneuvers into account when designing new skills, and reverse-engineering existing ones – a lot of fancy tricks means a harder skill.

Note that it's not clear how many maneuvers belong to existing skills, even going by a simple "if it's mentioned, count it" method. COSH attempts to count the maneuvers Martial Arts 2E gives existing skills, using two simple ground rules: a) discount cinematic maneuvers; and b) add two maneuvers the book forgot: Weapon Strike and Weapon Parry, the armed equivalents of Hand Strike and Hand Parry.

Doing that turns up roughly 28-30 maneuvers for Karate, 20 for Brawling, 15 for Fencing, 12 for Judo, 8 for Boxing, 7 for Wrestling, and 9 for the typical weapon. Your counts may vary, but those are the numbers this text will go with.

Hypothetical items

Some enhancements and limitations are hypothetical, such as Large Dodge Bonus. These fit no existing skill, but open the door for designing new ones. Disallow these as you like, or use with caution, or go wild and make up more of your own.

The Enhancements and Limitations

Here's your catalog. Time to go shopping!

Notes on Enhancements and Limitations

"Why is that on the list?"

A few of the enhancements and limitations, or their ratings, may look dubious – but they're there because, well, GURPS suggests their existence. Why is Muscle-Powered Ranged a big enhancement? Because Bow and Blowpipe are harder than other ranged skills. Why is Light Weapon made a limitation? Because Knife is easier than Shortsword, for no reason that I can see other than the small weapon size.

Unarmed skills are given a great big blanket limitation of -4. Why? Because when you total up the abilities they confer, GURPS' unarmed combat skills are far, far easier than an equivalent armed skill would be. Whether that makes sense or not, these skills get a huge limitation here in order to produce GURPS-like results.

Specific Notes

Encumbrance Penalties

In GURPS, this takes the form of a binary "must have Light encumbrance or lower".

However, the game is unclear on what exactly happens with higher encumbrance – does the skill "disappear", or what? Work this how you will, but COSH will suggest an alternate, more flexible rule borrowed from GULLIVER: A skill with the Encumbrance Penalties limitation may be used while encumbered, but takes encumbrance level as a penalty on skill for all purposes.

Grappling

The core of wrestling-type skills. Grappling can be further broken into Offensive and Defensive Grappling. The former lets you use skill to make offensive grappling moves, and is the prerequisite for the Special Abilities for Throws and Locks, as well as maneuvers like Choke Hold. The latter lets you use skill to resist those same abilities.

Grappling requires full Off-Hand Use (+1); Offensive or Defensive Grappling can get by with Offensive or Defensive Off-Hand Use (+1/2), respectively.

Large/Small Damage Bonus

This is derived from the Brawling, Boxing, and Karate rules, and will be a common enhancement for any unarmed striking art. It could be added to armed skills as well; try it out, but keep an eye on whether the combination is unbalancing.

Unlike the Dodge Bonus and ST Bonus enhancements, Damage Bonus has no built-in limits on use (other than use of the appropriate weapon, or no weapon, as the skill dictates).

It's tempting to further tweak the enhancement for use with only punches or kicks, or swings or thrusts, by cutting the value of the enhancement by -1/2. This could be unbalancing, though; after all, the full-fledged Single Mode limitation only nets you a -1. Use with care.

Large/Small Dodge Bonus

This is patterned after the Dodge bonus for Boxing. Following Boxing's lead, the enhancement must have built-in limits on use. (An unlimited version could be unbalanced, and is not offered in these rules.)

Boxing's bonus applies only to bare-handed and thrusting attacks, and not swung or ranged attacks (or kicks, presumably). When adding this enhancement to a skill, use Boxing's limits as a guideline. A rule of thumb: Lump attacks into broad categories: punch, kick, swung weapon, thrust weapon, ranged weapon, etc. Pick two as the attacks vs which the Dodge bonus applies.

More exotic skills could use categories like near attacks (Range C or 1), far attacks (Range 2+), smaller foes, same-size foes, larger foes, and so on.

Large/Small ST Bonus

This is derived from the ST bonus GURPS gives to Wrestling. The bonus applies only to a limited range of uses, which must be defined. In the case of Wrestling, this is the range of wrestling-like moves, such as grapples, takedowns, pins, and breaking free. (Side note: find plenty of spiffed-up rules for these actions here.)

The enhancement "ST Bonus (single use)" can be applied to only one action, such as breaking free. Specify the single action to which the ST bonus applies.

Be wary of allowing the ST Bonus enhancement for strikes; these may prove unbalancing.

Light Weapon

This applies only to armed skills, not ranged or unarmed skills.

Limited Improved Parry

Use this for a skill that offers Improved (2/3 skill) Parry under some conditions, but a normal (1/2 skill) Parry under other conditions. Use Katana as a guide.

Limited Parry

Use this for an all-round poor Parry, or for a skill with its default Parry (whether normal or Improved) under some conditions, and a lesser Parry under other conditions. Perfect examples are Brawling and Boxing, which cannot effectively parry some weapon attacks (and kicks, in the latter case). Define the conditions of the limited Parry, using Boxing and Brawling as guides.

No Blows

Note that this is not named "No Attack". It means there's no strike, whether swing, thrust, punch or kick – but there may be wrestling-type attacks such as Grappling, Slamming, and related maneuvers.

Off-Hand Use

The ability to use the off-hand without penalty for any of the skill's actions. Skills may choose to use the cheaper, more limited Offensive Off-Hand Use, required for any offensive grappling moves and a useful addition to punches, or Defensive Off-Hand Use, required for defensive grappling moves and a useful addition to parries.

Single Mode

The skill covers only punches or kicks if unarmed; swings or thrusts if armed. This applies only to skills that include offensive blows.

Slamming

The ability to perform, or resist and evade, slams and pushes. It can be further broken into Offensive and Defensive Slamming. Slamming does not require Off-Hand Use.

When one character attempts to move through a foe's hex (see Evading, BS 113), Offensive Slamming helps prevent such evasion (i.e., block the foe). Defensive Slamming helps perform the evasion (i.e., get by the foe's block).

GURPS does not cover slamming and pushing in much detail; the low enhancement costs reflect both the simplicity of the moves and their limited utility.

Slamming is primarily used in unarmed skills, though some armed exceptions, such as Shield, seem to make sense.

Special Ability

Throws, Locks, and other powerful abilities are considered a Special Ability enhancement, either +1 or +1/2. The appropriate Special Ability allows the skill to include the covered maneuver(s), or otherwise adds the covered ability. However, maneuvers requiring a Special Ability still count against the total number of maneuvers the skill may have!

Notes on Skill Building

Limit on limitations

Stacked limitations on blows can only reach -1 1/2, not -2, as long as some offensive blow remains. Likewise, stacked limitations on parrying can only reach -1 1/2 as long as some parrying ability remains. That's because No Blows or No Parry is each a -2 limitation.

Example: You add Single Mode: swing only (-1) and Reduced Damage (-1) to your skill, for weak swings. The combination only nets a -1 1/2 limitation, not -2; the full -2 is reserved for the No Blows limitation.

Building wrestling-type skills

To build a grappling skill like Wrestling or Judo that does not use strikes, start with an unarmed skill. Add No Blows (-2). Then add Grappling, Slamming, and Special Abilities like Locks and Throws, as appropriate. Don't forget to add Off-Hand Use to Grappling (or the limited Offensive/Defensive Off-Hand Use to Offensive/Defensive Grappling).

Selecting a skill's maneuvers

Once you've invented or modified a skill, you have another fun task: picking maneuvers, up to as many as the skill allows. Rules of thumb for making selections:

a) Choose maneuvers that fit the skill. Set sensible prerequisites: kicking moves require that the skill have kicking ability, wrestling-type moves require that the skill have grappling ability, and so on.

b) At the GM's discretion, allow limited exceptions to the above – perhaps one exception per skill. Existing examples include Leg Grapple in Brawling and Karate (even though these do not otherwise offer grappling techniques), and Drop Kick in Wrestling (which does not otherwise allow kicking). If abuse is a worry, the GM might choose to make such an exceptional maneuver count as two maneuvers against that skill's total number, or place limitations on the maneuver's capabilities, or otherwise come up with restrictions (including outright veto) against maneuvers that don't fit the skill.

c) Allow and disallow cinematic maneuvers at your discretion. An in-between solution: make a cinematic maneuver available, but have it count as two maneuvers against the skill's total number.

d) For simplicity, maneuvers treated as Special Abilities in these rules still count against the skill's total number of maneuvers. For example, a skill that offers the Arm Lock and Finger Lock maneuvers must include Special Ability: Locks and include those two maneuvers in its list of maneuvers.

See "Optional Stuff" below for more ideas on using – or ignoring – maneuvers with COSH.

Sample Skills

Here are a number of skills worked out as examples. After the skill name is a list of included enhancements and limitations, then notes where applicable, and finally, the end difficulty level. A few of these purposely veer from GURPS writeups, as you'll see.

Read up, then go out and invent Two-Handed Hobbit Kneecapper skill or what have you.

Some Basic Skills

Default average skills

Skills including Broadsword, Shortsword, Two-Handed Sword, and Polearm have none of the listed enhancements or limitations. These are default Average skills.

Knife

Light Weapon (-1). Easy.

Spear

Spear covers one- or two-handed use, but presumably uses thrusts only.

Multiple Grips (+1), Single Mode: thrust only (-1). Average.

Staff

Improved Parry (+1). Hard.

Unarmed Skills

Brawling

Small Damage Bonus (+1), Many Maneuvers (+1), Improved Parry (+1), Off-Hand Use (+1), Limited Parry (-1), Unarmed (-4). Easy.

Karate

Large Damage Bonus (+2), Tons of Maneuvers (+2), Improved Parry (+1), Off-Hand Use (+1), Encumbrance Penalties (-1), Unarmed (-4). Hard.

Ranged Skills

Bolas or Lasso

Flexible Weapon (+1), Few Maneuvers (-1). Average.

Bow, Blowpipe, or Sling

Muscle-Powered Ranged (+2), Few Maneuvers (-1). Hard.

Crossbow or Guns

Few Maneuvers (-1). Easy.

Thrown Weapon

Most variations of this have Few Maneuvers (-1). Easy.

Other Interesting Skills

Net

A ranged skill, net covers a variety of sizes and presumably requires two hands (do not add Multiple Grips).

Flexible Weapon (+1), Many Types (+1), Few Maneuvers (-1). Hard.

Shield

This skill covers several sizes of shield, but treats a buckler as a different skill (i.e., don't add Many Types). And don't add No Parry; obviously, Parry in the context of shields refers to Block!

Off-Hand Use (+1), Single Mode: thrust only (-1), Few Maneuvers (-1). Easy.

A few invented variants:

Offensive Shield: Skill may be used to make or resist slams and pushes, as well as make bashes. A good choice for Spartan soldiers, who made an art of shield walls and rushes. (Speaking of which, a Shield Wall maneuver sounds nifty; anyone have a suggestion?)

Off-Hand Use (+1), Slamming (+1), Single Mode: thrust only (-1), Few Maneuvers (-