Summary of ways to handle power-vs-weight in GURPS creatures

Responding to this thread on the SJG forums, I started listing the different ways to handle the design issue of power-vs-weight in creatures. But my would-be post was getting farther from the focus of the thread (handling of armor and creature size), so I’ll place it here instead.

The topic

Creatures have vastly different ratios of power to weight. Here’s a summary of available ways to handle that, in increasing order of detail:

a) Ignore it! Done. : )

b) Follow the 4e BS19 guidelines: just wing some adjustments to Move etc. that feel right. This is usually good enough!

c) Per b, but use some rough guidelines for the adjustments (per GULLIVER Mini).

d) Handle body weight above some baseline explicitly as encumbrance, with all appropriate effects (per GULLIVER for 3e).

e) Per d, but also create appropriate “negative encumbrance” effects for weight under the baseline (per GULLIVER for 3e). Make up some appropriate exceptions for low gravity, buoyancy, or other special cases of low or zero weight (where mass would limit the benefit to be gained).

f) Per e, but fancily incorporate weight and mass throughout (per GULLIVER for 3e), not just in special cases.


Going as far as f is nifty in that it handles everything with no special considerations – but the extra detail is rarely called for! Me, these days I’m all about c, and think most players will be happy with b.

But while 4e BS19 sticks to complexity level b, GURPSologists will note that level d was first a GURPS invention, applied in 3e for fat, high density, or high gravity. Level e also appeared first in GURPS, though in a very small way, in the form of some simple effects of low gravity.

GURPS 4e still uses a form of d for the effects of high gravity. So the GURPS default isn’t entirely the laid-back, “just wing it” approach of b!

One other possible consideration

I’ll label this g, though that doesn’t quite fit the above order; it’s an option that can be added to d, e, or f.

g) Incorporate body weight into encumbrance, but with body weight having less effect than the weight of carried loads. Suggestion: halve the body weight that’s over (or under) the encumbrance baseline.

Using g, assume that the the game’s encumbrance system is set up for loads with less-than-optimal bulk and balance: clumsy backpacks, carried weapons, temporarily hefted items, and other protruding, shifting loads. An extra 100 pounds of your own flesh, on the other hand, stays in place close to you (we hope!), and so is less encumbering than the 100-lb. body of a colleague slung over your shoulder.

Net effect: g lets you realistically keep body mass and weight as an express factor in physical prowess, but with milder effects. That means less extreme mobility in small and/or powerful creatures, and more ease in building big creatures that aren’t on the verge of collapse.

It’s mentioned in GULLIVER for 3e, but not used as a default anywhere therein.


So there you go: plenty of options for handling (or not handling!) that power-vs-weight consideration in creatures. Go forth and design!


GULLIVER 3e and Mini for 4e


  • Douglas Cole

    One suggestion: don’t halve the value of inherent encumbrance…use a bulk/unweildliness modifier for carried loads.

    So, lifting or carrying a perfectly balanced 40lb load, for example in a TL8 LBE vest, is worth 40lbs. A TL6 equipment ruck, poorly distributed, might be 60lbs worth (A bulk modifier of 1.5), while piling all kinds of crap in a sack and slinging it over one’s shoulder might count as 80lbs worth of encumbrance, as it bounces around and hampers mobility, etc.

    • tbone

      Well, I started by asking what sort of loads the GURPS encumbrance system is set up for. For lack of any pronouncement from the designers on that, I assumed “mixed load”: some well-distributed stuff like armor or properly-done backpacks, plus poorly-distributed stuff like weapons in hand, sacks of treasure, overstuffed backpacks, etc.

      Starting with that assumption leads to no modifier for “typical” loads (normal backpacks, weapons in hand, etc.), a weight divisor for exceptionally well-distributed loads (body weight), and a weight multiplier for unusually bulky/clumsy ones. Armor should probably come under the same divisor as body weight, but it’s simplest to keep no modifier for just about everything, and use modifiers only for the extreme cases (body weight one one end, really clumsy loads on the other). That leaves minimal modifiers actually coming up in play – and one of those, that for body weight, only comes up once during character generation.

      Also, I like the assistance that the body weight divisor provides in keeping big/small designs from hitting the extremes of encumbrance too quickly. It’s a nice design aid, especially for dinosaurs etc.

      “Upping” all the multipliers, with body weight at x1 and many carried items getting x1.5 or more, is fine in theory too. But for better or worse, it’ll boost overall encumbrance above what the game designers intended.

      So in the end, I like the way I outlined as it doesn’t meddle too much in overall encumbrance levels, and it’s simple by not using modifiers often at all. (Then again, “simple” here does mean “less detail”; for example, I’m not allowing for any difference so far between the professionally-packed backpack and the generic sloppy one.)

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