combat without actual defense rolls?

[sn0wball]

Originally Posted by ericbsmith

Setting aside any an all rules arguments and probability arguments for a moment, I think there is an important part of the defense roll that involves player psychology. It feels good as a player to feel like you can do something about a given situation, and a defense roll means that the player has some influence on the outcome of whether or not their character gets hit by an incoming attack. Taking away that control is not a good thing, especially for players that are used to having that control. It's one thing to be annoyed because the blow you thought you landed got parried, it's an entirely other thing to be annoyed because an NPC landed a blow on your character and there's nothing you can do about it.

Additionally, this means that any general rules the game system has to influence your own rolls can be applied to defense rolls. In GURPS terms, what use is Luck if it doesn´t help you evade attacks?

[weby]

Originally Posted by sn0wball

Additionally, this means that any general rules the game system has to influence your own rolls can be applied to defense rolls. In GURPS terms, what use is Luck if it doesn´t help you evade attacks?

In such a situation luck applies to the attackers roll. See B66.

"Your Luck only applies to (snip) or when you
are being attacked (in which case you
may make the attacker roll three times
and take the worst roll!)."

[ericbsmith]

Originally Posted by ericbsmith

Another option if you keep a computer or tablet at the gaming table is to make a spreadsheet or other utility where you simply input the attack and defense numbers and it pops out the table lookup for you.

And... because I could and love Excel way too much I created just such a spreadsheet:

http://gurpsland.no-ip.org/zip/AttackTable.zip

[AlexanderHowl]

The problem with subtracting defense is that defense trumps offense in GURPS (except in the case of a critical success). If you have two characters with combat skill 24 (not unusual in my games), they both have a parry of 16, allowing them to parry around 88% of the attacks. If you replaced defense with a penalty equal to (defense-10), the probability of a successful defense drops from 88% to 2%, as the attacking character will only suffer a -6 to attack, reducing their skill from 24 to 18. In effect, the probability of a successful attack increases over eightfold, from 12% to 98%.

A better alternative would be a penalty equal to Defense. In the case of the two combatants with combat skill 24, a -16 to attack would give them an effective skill of 8, which would give them a probability of around 25% to succeed on the first attack. While it is still a doubling in the success rate of the attacker, it is better than an eightfold increase.

Of course, this may make the defense for lower value characters seem much better, but that would be an illusion. The masters would suffer -10 to hit against a character with dodge 10, meaning a success rate of 90%. In the old system, the success rate would have been 55% without any deceptive attacks or feints. You still end up with a faster system for highly skilled characters (though it becomes a much slower system for low skilled characters).

[ericbsmith]

Originally Posted by AlexanderHowl

A better alternative would be a penalty equal to Defense.

That would overly penalize mid-skill combats. Two combatants with Skill-12 have Parry-9, so would only hit on a 3 or less using that method when the real chances of a successful attack there is almost 50% (46.99%, to be precise).

[AlexanderHowl]

But the other formula would increase the effective skill of the mediocre fighter to 13, which would mean that their probability of success would increase to 83% or so.

[ericbsmith]

Originally Posted by AlexanderHowl

But the other formula would increase the effective skill of the mediocre fighter to 13, which would mean that their probability of success would increase to 83% or so.

I already said I don't like that formula either, but 13 is closer to 12 than 3 is (and 83% is closer to 74% than 0.5% is).

[Gollum]

Originally Posted by ericbsmith

I already said I don't like that formula either, but 13 is closer to 12 than 3 is (and 83% is closer to 74% than 0.5% is).

Yes. And I also said that I abandoned that formula, which was originally made for another roleplaying game system than GURPS ... GURPS as written remains far much better - which is why I go on playing it rather than playing my self-designed system.

I would like to precise something, though. In my formula, the defense is not calculated the usual way (half skill + 3). It is the full skill.

Thus, two warriors with broadsword-12 would have a defense score of 12, which would give them exactly 50% chance to hit each one another. Exactly as two warriors with skill-10 or two warriors with skill-24.

Having said that, I did recognize that it completely changes odds and that it even breaks when the difference between the two warriors becomes 7 or higher (the effective skill of the lower one becomes less than 3).

[edk926]

Well if someone has skill-20 and is fighting someone with skill-12, you'd expect the 20 person to quickly waste the other person anyway.

[Gollum]

Originally Posted by edk926

Well if someone has skill-20 and is fighting someone with skill-12, you'd expect the 20 person to quickly waste the other person anyway.

Right. But with my rule, the one with skill-12 would have 0% chance of attacking (effective skill under 3: no roll allowed) and would only defend with a critical success.

Of course, that could be corrected by still allowing a roll for the attack and, so, a successful attack in case of critical success.

But the chance would remains too much low. The character with skill-20 would have about 98% chance to hit while the one with skill-12 would only have about 2%. While with EricBSmith's table (based on GURPS as written chance), it actually corresponds to a roll of 12 (for the skill-20 character) vs a roll of 6 (for the skill-12 character).