GURPS Unified Theory of Hitting Stuff (GUTHS)

Big edit 2020-09-05: Slight rewrite to accommodate a recent clarification of a long-standing GURPS rule (a recent clarification to me, anyway!):

In GURPS (and its offshoot Dungeon Fantasy Roleplaying Game (DFRPG)), a target’s SM acts as a TH modifier for ranged and melee attacks against that target. That “melee” part is the clarification: it’s not made clear in the Basic Set (see this post in this forum thread), and many players (including me!) always assumed that the Basic Set didn’t make SM a TH mod in melee combat. But the official rule is that SM is a TH mod for melee attacks and ranged weapons alike.

So there it is. That revelation has prompted an update to this article. In particular, the article’s core achievement of “unifying” GURPS‘ ranged and melee assumptions into a single procedure is lessened; its suggestion that the game should apply SM as a TH mod in both ranged and melee combat becomes moot, as the game already does so!

But the article’s further workings, particularly those leading to the suggestion that “relative SM” is the ideal way to handle SM as a TH mod in melee, still stand.

Intro: Grand Unification Theory

Imagine the following questions about combat in GURPS. (Fiddly, thoroughly non-pressing questions about special-case oddities, yes, but questions all the same.)

  • SM acts as a modifier to TH in combat. The resulting near-impossibility of shooting at a mosquito (SM -15?) sounds fine, but that modifier applies to melee combat, too – so how can you possibly slap that bug?
  • How can two tiny combatants – whether small critters or mini PCs – possibly punch each other when both face a near-impossible TH mod?
  • What happens when an attacking weapon is larger than its target?
  • Getting up close to shoot a target naturally improves your ranged attack TH – until you hit a mysterious threshold of two yards. Why does getting closer than that – such as shooting at a target from mere inches away – do nothing to aid TH?
  • If getting closer than two yards to a target offers no benefit, then again, how could tiny shooters ever manage to blast each other?

All is answered: there exists a GURPS Unified Theory of Hitting Stuff (or GURPS Unified TH System; it’s GUTHS either way) that does the job. Okay, it’s not in the rules, and the name is my own goofy coinage. But this isn’t just some rules bit I’ve had posted on my site for ages, nor even much of a “house rule” at all. It’s a simple interpretation of existing GURPS rules that instantly sets all the above running smooth as a duck, 100% rules-as-written compatible.

The simple code

Enough of that. Here’s the GUTHS interpretation of how things get hit:

  • 1) Whether GURPS knows it or not, its ranged and melee combat actually use all the same rules for TH! The core assumptions:
    • 1a) All TH, ranged and melee, uses the Size and Speed/Range table. Easy!
    • 1b) The Range column extends (well, should extend) its mods equally in both directions, offering bonuses for close range under two yards as well as penalties for range beyond two yards (just as it was nicely handled in 3e). On your 4e table, replace those dreary “+0” entries with the appropriate bonuses!
    • 1c) Range can logically be as close as circumstances allow, such as mere inches if you shoot a padlock to break it, or if you slap a bug on your arm; the appropriate big TH bonus applies, typically working miracles to offset a big TH penalty for small target size. But, when making regular attacks in combat against an active target (what with movement, uncertain distances and positioning, and need for maneuvering space), effective Range (melee or ranged) can only be as close as the attacker’s SM-based height/length (i.e., two yards for a human).
    • 1d) For both ranged and melee TH, target Speed may or may not be relevant: if the target is not in combat with the attacker, its Speed generally counts for Speed/Range purposes. But if the target is engaging the attacker, it can be considered to have no Speed for TH purposes.
    • 1e) This may be a wholly new addition to GURPS combat, but it’s a logical one: when a weapon with a large striking area strikes a small target, use the larger of the two as the effective target size. That covers wide flyswatters hitting tiny flies, or room-wide dragon-flame jets washing over PCs.
  • 2) A couple of logical ranged-vs-melee considerations crop up, as follows:
    • 2a) While both ranged and melee attacks have an effective minimum Range (1c above), melee attacks also have a short maximum Range (typically a yard or two, longer for polearms and pikes).
    • 2b) From 2a, melee attacks face a cap on effective target size: any target size outside of a melee attack’s reach is meaningless as a target, and logically can’t aid TH. For simplicity, call that maximum effective target Size the attacker’s SM +4. (For a little more detail, that maximum might fall to +3 if your weapon is very short, i.e., Range C, or whatever the equivalent short range is for your size.)

Outcomes

From the above, the following outcomes fall into place:

Ranged combat

For ranged combat, all the above boil down to “rules as written”. Just follow standard 4e rules, using Speed (if relevant), Range, and Size (target SM) normally.

One important change occurs, though: do allow TH bonuses for Range closer than two yards, if that Range can be reasonably achieved. It can’t, for SM 0 humans shooting active targets (i.e., for most ranged combat situations); minimum range is the human’s height of two yards, which means no super-short-range TH bonus for claiming “I dash in and put my gun really close to the bad guy!” You can read 4e‘s stance of “no bonus for close Range” as reflecting that common situation.

But if a shooter can logically get closer to an unmoving target, or if a small shooter can shoot an active target from closer than two yards (down to an effective range as close as his own height/length), do allow the appropriate close-range bonus.

This simple change makes many unusual situations – like those tiny gunmen having a close-range shootout, or a character shooting a lock from inches away – completely workable!

Melee combat

Melee, too, boils down to existing rules as written for typical situations. Target Speed is typically irrelevant in melee; ignore it, per normal GURPS melee.

Note, though, that under the above assumptions, each fighter strikes from an effective Range appropriate to his own SM, at a target Size of the foe’s SM. The net result of this is the same as using relative SM as a TH mod: the difference in SM becomes a bonus for the smaller combatant to hit the larger, and a penalty for the larger to hit the smaller. Nothing changes from normal GURPS rules for two human-like fighters, but odd situations (like two tiny fighters) now work!

(Note: this relative SM rule is an official option in the GURPS 4e FAQ, thanks – at least in part – to Your Author lobbying for it from the GUTHS perspective. Though I’m sure many others have independently realized that it’s the sensible way to handle size in melee.)

A couple of little things:

  • Don’t forget to place a maximum +4 on a smaller foe’s TH bonus for an attack vs a large target. (This is for melee only; 2b above doesn’t apply to ranged combat, and thus there’s no cap on your ranged attack TH bonus to hit a large target.) 
  • Remember that you can hit small targets more easily by using the larger of weapon SM (based on its “striking area”) or target SM (from 1e above).

That’s it

With those simple interpretations in place, all the initial questions about size, speed, range and TH are answered. Dwarves vs Giants in melee, ants brawling with ants, creatures of every size shooting away at each other from any conceivable distance; everything is answered and everything works.

  • A knife-fight between two Pixies? It now works the same as a fight between two humans. (Except I’d pay more to see the Pixie brawl.)
  • Shooting a padlock from inches away? Sure; it’s a tiny target, but you can take a big bonus for teeny Range. Just watch for shrapnel . . .
  • Need to capture that rare valuable butterfly, or deal with a teeny pixie pest? Use a weapon perfectly designed to overcome that vexing tiny SM by offering a big striking area: the butterfly net.
  • Need to slap a mosquito? Same deal: tiny target, but you can take a big Range bonus for having sneaked that slapping hand up close. And use the hand’s SM, not the mosquito’s, as the effective target Size. Also don’t forget AoA (Determined) and Telegraphic Attack (if the bloodsucker is too busy feeding to roll a defense). In the end, it’s an easy shot with GUTHS!

No existing rules have been mangled to enable the above effects; the rules have just been examined and made sense of. And ranged and melee TH are now unified in all aspects, which is cool, because . . . well, just because.

GUTHS. Spread it far and wide.

6 Comments

  • Captain Joy

    tbone wrote:

    Melee combat

    Under the above, melee also continues to follow standard procedure. Target Speed typically is irrelevant in melee; ignore it. Each fighter strikes from an effective Range equal to his SM, at a target Size of the foe’s SM. The net result of this is the same as using relative SM: the difference in SM becomes a bonus for the smaller combatant to hit the larger, and a penalty for the larger to hit the smaller. However, as described above, place a maximum +4 on the smaller foe’s bonus vs the large target.

    I would add to this final paragraph: “and remember to used the larger of attacker’s weapon’s SM or the foe’s SM when determining the larger foe’s penalty vs the smaller target.

    You might also add that the +4 maximum assumes the small foe has a weapong that extends his reach beyond 1/2 his size. So, if the smaller foe has no way to extend his melee attack range, e.g. punching, biting, a small knife, then a +3 maximum is more realistic.

    I know I’ve said it before, but *fantastic* stuff T-bone.

    • tbone

      Ahoy, CJ. Thanks for the very kind message.

      I’ll make the suggested addition re using larger of weapon SM and foe SM.

      And as for the max SM + 3 vs SM + 4: Unless I’m mistaken, this isn’t part of the “official option” in 4e, which just offers a flat SM + 4. You might be referring to the original GULLIVER write-up on the topic, where I suggested a max SM + 2, or SM + 3. Since the 4e official option chose a +4 instead, I went with that in GUTHS, for compatibility.

      With a nod to my original rules, I’ll add a compromise in 2b): a flat +4, or a varied +3 to +5 depending on attacker Reach. I think +5 is getting awfully generous, but it all averages out to to the “official” +4, and should work fine in play. Look OK to you?

      • Captain Joy

        tbone wrote:
        And as for the max SM + 3 vs SM + 4: Unless I’m mistaken, this isn’t part of the “official option” in 4e, which just offers a flat SM + 4. You might be referring to the original GULLIVER write-up on the topic, where I suggested a max SM + 2, or SM + 3. Since the 4e official option chose a +4 instead, I went with that in GUTHS, for compatibility.

        With a nod to my original rules, I’ll add a compromise in 2b): a flat +4, or a varied +3 to +5 depending on attacker Reach. I think +5 is getting awfully generous, but it all averages out to to the “official” +4, and should work fine in play. Look OK to you?

        I think +5 is too generous. Maybe just add a parenthetical: “(although a +3 is probably more realistic for reach C weapons)” or something like that.

        • tbone

          My preference would be to keep my original, old +2 as the simple, all-purpose maximum for all weapons; and for more detail, sandwich bonuses around that: +1 for really short weapons, +3 for really long, +2 for everything else.

          But since Dr K decided upon +4 instead, that makes detailed sandwiching hard: +3 for short, +5 for long, +4 for everything else. And we agree that +5 is just sounding too big.

          Oh well, if sandwiching around +4 doesn’t work so well, I guess the next best may be as you suggest. I think I’ll work that in. (And anyone reading these comments can pick up alternate ideas to try.)

          Thanks!

  • Esteemed Visitor

    Aw, by the title I thought it’d be “Unified” as in joining To Hit and To Defend on a single roll…

    Well, a man can dream :C

    • tbone

      Hmm, that’d be the GURPS Unified Theory of Hitting And Defending (GUTHAD)…

      Single-roll TH and defense? I’m not interested myself, but there are plenty of examples in other RPGs; HERO System is one. For GURPS, I imagine it’d have to work something like a Skill roll, plus a big bonus (+10 or so?), minus the target’s AD. I’m pretty sure I’ve seen people on forums discussing such a mechanism… Whatever the negatives, I’m sure it’d play pretty fast!

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