I speculate that GURPS (and maybe The Fantasy Trip; I wasn’t around for that one) started with a fairly generic view of damage that incorporated penetration, blunt trauma, injury, and a certain amount of gamist fun. GURPS High Tech introduced the dependence on the square root of kinetic energy as a “damage” scale by giving the general rule of 20d = DR 70 = penetration of one inch of armor steel. I’m not sure from whence that one came, but I suspect David Pulver provided it to Mike Hurst.
All of a sudden, you had two different progressions for damage, and some projectiles (bows) were on the ST-based scale, while the more-easily-quantified set (guns) were on another.
Sometime around the year 2000, I started fiddling with Excel’s solver. I thought that if I could find enough penetration data, I should be able to take a priori data about projectiles (specifically bullets) and turn that into GURPS stats. The result got me a mention on TV Tropes (look for Arbitrary Gun Power), and was published in 2002. But it worked fairly well, and got me noticed by a few other gamers.
Anyway, THAT little adventure got me to notice that while firearms matched penetration of armor with known and quantifiable data – in this case the mass, velocity, and caliber of the bullet (from which you derive kinetic energy and momentum – that and cross-section are all you need to derive basic damage/penetration and a wound channel size modifier), weapons on the melee scale (things that you look up as “thr+2” or “swing+3” on the Damage Table on p. B16 of GURPS Basic Set, Fourth Edition) got pretty high penetration numbers pretty fast. Maybe too fast.
I once again scored a mention in TV Tropes by nearly breaking my brain (and Steven Marsh‘s sanity) figuring out how to do for bows and arrows what I did for guns. It was phenomenally more difficult.
OK, so I’ve covered arrows and bullets. What about sling stones? Swords? Maces? Polearms? Pointed sticks?
Um . . .
My previous post was an attempt to show how you could at least get the scaling of melee weapons right, where every doubling of ST also doubles penetration.
What you say?! GURPS ST measures applied force, and it goes as your ST score squared (Basic Lift is measured in pounds of force). Energy is force times distance, and if distance is more or less related to how far you can move your body (push-pull-twist-turn!), then doubling force should double deliverable energy, quadruple force is quadruple energy, etc. Then when you put this on the same sqrt(KE) progression as guns, you can arrive at a nice progression where ST 10 is about 1d, ST 20 is 2d, ST 40 is 4d, etc.
Hey, that’s damn playable. Even for me.
Well, that’s penetration, great. But injury? GURPS as-is is probably more right than wrong here when it comes to squishing meatbags. People are notoriously fragile (and strangely and unpredictably robust as well).
So then you get into wounds, penetrating trauma, blunt trauma, and other things.
Fortunately, GURPS already has the tools required to handle this.
It has a basic damage number that should be used to represent penetration.
It has damage type and damage size modifiers that I’d personally apply a bit differently (maybe that’ll be Part 3), but basically are a “wound channel severity” modifier.
It has armor divisors to represent something that penetrates better (or worse) than the raw energy might otherwise indicate.
With those things in mind, the only thing that’s really missing is a better way to represent blunt trauma and other non-penetrating injury.
Were I to start from scratch, I’d try and figure out:
Penetration rating, probably mainly based on energy. This would be GURPS’ “basic damage,” but possibly on a new scale. I like the “ST equivalent” number from the last post, since many weapons just act as lever arms, multiplying force. Multipliers are also nice because they allow the quite-simple “add +1 per die” type math, which is even easy in play.
Blunt Trauma rating, probably based on momentum and impact force. I think this is mostly what is done for hand weapons now, implicitly.
Armor Penetration modifier based on shape, hardness, or other factors. This is the source of my assertion that impaling weapons (a damage type I loathe) should probably get a (2) armor divisor, due to all their force being concentrated on a tiny, hard point.
Wound/Injury modifier based on the size and depth of damage. If I were really good, you’d incorporate some sort of “you have to achieve so much penetration before you can get to a Vitals type location.” That would help scale certain effects where you really NEED to go deep (Giganotosaurus hunting! Or a Frumious Bandersnatch)
I’d also have blunt trauma (including punches) be resisted by a HT roll, possibly influenced by skill. During the writing of The Last Gasp, one of my helpers ran a boxing match, and we decided that a HT roll to avoid actual HP of damage (but preserving the AP loss damage causes) from punches would make a LOT of sense, since even with boxing gloves, a typical 15-round boxing match as played in GURPS would kill both fighters. Extending this to all blunt trauma wouldn’t be too much of a leap, and if there were a penalty to HT rolls based on the rolled damage or something, that would keep maces and staffs scary. Alternately, padded hands might do the trick for bonuses to HT. People CAN get killed in fights, after all. They just usually don’t.
None of this is to say “GURPS is broken, wah!” It’s the best playable simulation out there that you can nod your head and say “yep, I get that” for most things. But when the tool of choice for penetrating DR 8 plate armor is “give me a sword” rather than “give me a spiked warhammer” (this one, not that one) or “grab me my gun,” then some head scratching might be in order!
The key in all this is to keep it fun and playable. All this crap needs to be subsumed into a table and calculated but once, during character generation or on obtaining the item the first time, and then never again. Even as ugly as The Deadly Spring was, the math is all in a spreadsheet (generously provided by Steven along with the issue of the magazine!) done up front.