GURPS101: Deconstructing Size Modifier

Guest Post by Sean “Dr. Kromm” Punch

First off, this one isn’t by me. It’s been a bit edited by me to fit in my blog, but is otherwise Sean’s words. This entire post stems from a conversation that was had in the GURPS Discord where Greyman asked: “Is there any way to make your head huge in GURPS so that your head doesn’t have a -7 to hit but like a -1 because of how massive it is?” And of course that sparked a huge debate about why that was a good idea or a bad idea, the ramifications of it, and ultimately what the cost should be for it.

Here is what I asked Sean: “What would you call a disadvantage that increased the skill of those hitting a hit location by +1 just as if they were targeting a larger being’s hit location?”

Here is what he had to say (off the cuff):

That is a hard call to make. For 36 years, GURPS has pointedly refused to put a cost on size. Fourth Edition treats it as a zero-cost feature: “It is neither an advantage nor a disadvantage to have a nonzero SM — the benefits and drawbacks tend to cancel out.”

There are indirect effects on point costs, meaning ST at high SM. That is all. The game stubbornly refuses to admit that being costly to feed, clothe, and domicile — and easier to see and hit — is a disadvantage, or that being tiny is an advantage because it makes you harder to see and hit, and should lower cost of living.

It’s hard to justify a point cost for being easier to hit in a single location when being easier to hit in *all* body parts is worth 0.

We could still try to dissect Gigantism: +1 to Basic Move is worth 5 points. To reach 0 points, all of the other bits and pieces should add up to -5 points.  Several of these feel like perks: cheaper ST/HP [1], an Intimidation bonus [1], and slightly better reach [1].

Others are disadvantageous: the rough equivalent of Unnatural Features 2 [-2], excess body weight without the upsides of Overweight/Fat/Very Fat seems like a quirk [-1], and so does paying more for clothing and armor (p. B20) [-1]. I’d add quirk-level Increased Life Support [-1] for the costs of food and lodging, though that’s left to the evil GM to inflict.

That leaves 3 points unaccounted for. Noisy suggests that each +1 to detect you/-1 to your Stealth is worth -1 point, so let’s use that for being seen. That leaves -2 points for being +1 easier to hit.

SM +1 [0] = Basic Move+1 [5] + Better Reach 1 [1] + Cheaper ST/HP 1 [1] + Intimidation+1 [1] + Easy to Hit 1 [-2] + Easy to See 1 [-1] + Expensive Gear (Food and Lodging) [-1] + Expensive Gear (Wearables) [-1] + Heavy [-1] + Unnatural Features 2 [-2]

Bigger Hit Locations

From there, we look at breaking it down by location. I’d go with the percentages Partial gives for DR (p. B47), meaning:  Torso: -1.8 points.   I’d call that -2 points because it includes the vitals and is the usual target of 90%+ of attacks. So, torso and the whole body are the same — but the whole body always hides the price in the price of SM I worked out, so we have room to fudge.

Both Arms or Legs: -1.6 points.
Vitals or Groin: -1.4 points.
One Arm or Leg: -1.2 points.
Both Hands or Feet: -1.2 points.
Face or Neck: -1 point.

I’d call any one of those -1 point. It’s slightly odd that one and both arms or legs get the same cost, but “one huge limb” is weird anyway.

Skull: -0.6 point.
One Hand or Foot: -0.4 point.
Eye: -0.4 point .

I’d ignore the one hand/foot case as too weird to matter. Call either of the other two -1 point per +2 to hit the body part. Again, while a geek might find it strange that “skull, or eye which is like skull but harder” are the same, the eye is clearly scarier.

The obvious name is “Easy to Hit.” Easy to Hit (All or Torso) is -2 per +1, Easy to Hit (almost all other locations) is -1 per +1, and Easy to Hit (Skull or Eye) is -1 per +2.

Picking Over The Bones

When I was pricing out the cost of “easy to hit” on my own I instantly went to a quirk. It seems like a quirk thing even though some versions are better or worse than others. I’m pleased to see Sean agreed with me. (I’ll note Cole Jenkins ALSO settled on a quirk when he poked the same problem hours ago.) My end was “it’s probably worth -1 to -4 points per +1 to hit the location.” I considered using a metagame version of Susceptible as well since while odd, it had a similar cost.

Detractors are going to point out that a bonus to hit the head or vitals means more damage…but they’d mean more damage for a bigger creature too and they don’t get any cost break for that so neither should this. Giving a bonus to hit doesn’t mean you’ll hit it. It just means what your hitting is more likely to be hit. That’s it.

I’ll also note that the Born Biter feature from GURPS Martial Arts (p. 115) wasn’t mentioned, but that seems like a perk (Can Grapple at +1 SM) and a quirk (Face is easier to hit) which clocks with everything else.

Posted in GURPS 101 and tagged , , , , .


  1. Am I the only one who thought of the big headed tiny titans from Attack on Titan when I read that opening break down heh? Yeah, I would of figured that born biter would of been the go to unless they wanted a huge ol noggin but normal sized mouth… in which case…. why do you hate everything pure and good in the world you monster?

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