Is there something about the slam rules I'm missing?

[zoncxs]

You forgot a few rules, Page 432 of Basic Set. Specifically, The struck object cannot inflict more dice of damage than the striking or falling one. So the most the impala can do is what the cheetah did, 2d.

Also, the cheetah can do an AoA Strong for +2 damage. That gives and average of 9 for the cheetah and 7 for the impala. The cheetah has a higher chance of knocking the impala down.

[Talonos]

Originally Posted by zoncxs

You forgot a few rules, Page 432 of Basic Set. Specifically, The struck object cannot inflict more dice of damage than the striking or falling one. So the most the impala can do is what the cheetah did, 2d.

It took me an embarrassingly long time to find that rule, especially given that I knew exactly what I was looking for. Under "Head-On", under "Collision angle"? What a weird spot to put it.

[Phil Masters]

It’s probably my background in Hero System, in which Move Through is a popular attack option, but I’ve always considered the GURPS Slam rules to be deeply broken. There’s just no way to represent the classic bruiser move of putting your shoulder down and smashing into someone (or something), without a lot of fractured shoulders.

And by the way, no cheetah will use any attack mode that inflicts damage on itself. They’re dangerously fragile creatures. Trip seems indeed to be their opening attack of choice, and the rules should probably allow them to execute a full Move and Trip with a fair chance of success.

(Not guaranteed success, of course. Most big cat hunts end in failure and all that.)

[sir_pudding]

The DFRPG slam rules may produce more satisfying results and dedicated pouncers (not cheetahs, but other cats, sunspiders etc.) benefit more from Sumo Wrestling than Brawling. Also for pouncers, you should probably just use the jump distance as the impact velocity.

[Pursuivant]

Originally Posted by Phil Masters

Trip seems indeed to be their opening attack of choice, and the rules should probably allow them to execute a full Move and Trip with a fair chance of success.

Possibly a "Running Trip" maneuver that allows a Move and Attack maneuver combined with a Trip?

Alternately, a variation on the Sweep technique, but where the attack uses their body rather than a limb to take down their foe.

Originally Posted by Phil Masters

(Not guaranteed success, of course. Most big cat hunts end in failure and all that.)

On stat that I've heard repeatedly is that the failure vs. success rate is 20:1.

Even odds of success with Stealth-12 to 15 vs. Vision or Hearing 12-15 gives a failure rate of 50%.

After that, any technique or attack which succeeds on a 6- (~9% total chance of success) with no defense allowed by the defender or 7- (~16% chance of success) vs. Dodge 9 (~37% chance of success) gets you into the right statistical area.

Given that a big cat's initial attack is going to be devastating (~1d cut biting and/or claws + slam/pounce) and possibly provoke a Fright Check, combat is going to be one-sided unless the feline badly messes up its Grapple attack, the prey animal Breaks Free, and gets in a good kick or strike with its horns or teeth on its way to safety.

As for Fright Checks, while getting stalked or chased by a predator, or seeing other animals (even "close friends or loved ones") getting killed, is "normal scary" for animals actually being the on the Menu Special is on another level. Animals which regularly get into scraps (anything with Combat Reflexes, or generally ornery like baboons, pigs, or cape buffalo) should be immune to Fright Checks if they're attacked by a predator unless they're Surprised. Animals who don't regularly engage in combat except for dominance fights might easily panic.

I agree that "flailing" is usually a Break Free attempt, but sometimes you see a prey animal just give up if a predator's got it in a hopeless situation (i.e., pinned and with a solid grapple to throat or muzzle). This might be an attempt to Evaluate or conserve its energy, or the effects of Shock, but it could also be a failed Fright Check.

[Phil Masters]

Originally Posted by Talonos

It took me an embarrassingly long time to find that rule, especially given that I knew exactly what I was looking for. Under "Head-On", under "Collision angle"? What a weird spot to put it.

Remember, GURPS started out as a system for handling fantasy warriors smacking each other with sword and board. Other combat tends to look like an aftermarket bolt-on sometimes — and bolt-ons can be untidy.

[malloyd]

Originally Posted by Phil Masters

Remember, GURPS started out as a system for handling fantasy warriors smacking each other with sword and board. Other combat tends to look like an aftermarket bolt-on sometimes — and bolt-ons can be untidy.

And they predate most of the unarmed combat rules, which is another problem. A slam will never happen at relative velocities anything like as high as you hit something with, say, your leg in a kick, and of course the target of a kick is substantially heavier than your leg is, and yet kicks don't fracture your leg....
I think the problem is the knockback rule [did] already exist, and damage was defined on the basis of that, aiming at causing both parties to be knocked back a lot of the time (because pushing an opponent is much of the point, and if you are using a slam to shove him over a cliff edge you kind of want the rules to stop you if not push you back the other way), and this really doesn't work very well. Note how Shove basically abandons linking damage to knockback. That's really what Slam should do, with some different method of calculating actual damage, something based on thrust like any other unarmed attack would probably work OK.

[sir_pudding]

Originally Posted by malloyd

That's really what Slam should do, with some different method of calculating actual damage, something based on thrust like any other unarmed attack would probably work OK.

Like thr-2 plus the SSRT modifier for distance moved that turn?

[Rupert]

Originally Posted by malloyd

I think the problem is the knockback rule [did] already exist, and damage was defined on the basis of that, aiming at causing both parties to be knocked back a lot of the time (because pushing an opponent is much of the point, and if you are using a slam to shove him over a cliff edge you kind of want the rules to stop you if not push you back the other way), and this really doesn't work very well. Note how Shove basically abandons linking damage to knockback. That's really what Slam should do, with some different method of calculating actual damage, something based on thrust like any other unarmed attack would probably work OK.

That would make it a variation on the Shove rule. Possibly just a Shove with a bonus to 'damage' for movement.

[Varyon]

I've always felt the primary issue with the Slam rules is that they basically assume the attacker is just running into the target, and the bonus from Brawling or Sumo Wrestling really isn't enough to differentiate between that and purposefully slamming into someone using your shoulder or similar. A proper Slam should basically hit the target with a striking surface of some flavor, which gives a bit of a boost to damage but, more importantly, markedly reduces the sort of damage the attacker suffers as a result. Slams should also typically have increased knockback relative to their amount of damage - whether that means using damage around the current value and giving it Double Knockback, or sacrificing some of the current damage and turning it into said Double Knockback (essentially making part of the damage into a Shove rather than a Strike), however, is a bit beyond me.

Originally Posted by sir_pudding

Like thr-2 plus the SSRT modifier for distance moved that turn?

Is that the way DFRPG handles it? Because that would be really easy - thr-4 for Move 1, thr-2 for Move 2, thr-1 for Move 3, thr for Move 5, thr+1 for Move 7, thr+2 for Move 10, and so forth.