Question about the maths behind attack roll and defense rolls

SolemnGolem · 04-13-2010, 07:21 PM

So I was leafing through the GURPS 4th ed. rules and looking at the opposed roll concept, which I liked. One thing stuck out at me.

Attack and defense are not opposed rolls. They're close, but the important issue of margin of success is missing. The way it is, Attacker rolls against her skill - failure means it fizzles, but success merely means Defender rolls against his skill. Defender does not apply a penalty to this roll based on Attacker's roll.

From a mathematical standpoint, what's the effect of this? If the designers had decided to make it an opposed roll, and applied Attacker's margin of success as a penalty to Defender's defense roll, how would the game be different?

The only thing I can think of is Defenders would fail more often - pretty much on par with the probability of standard opposed rolls as they currently stand. Did the designers remove the margin of success penalty to make the game less lethal? Has anybody applied the margin of success as a penalty, and how has that made your game run?

04-13-2010, 07:21 PM	#1
SolemnGolem Join Date: Apr 2010 Location: The Hall of Fallen Columns	Question about the maths behind attack roll and defense rolls So I was leafing through the GURPS 4th ed. rules and looking at the opposed roll concept, which I liked. One thing stuck out at me. Attack and defense are not opposed rolls. They're close, but the important issue of margin of success is missing. The way it is, Attacker rolls against her skill - failure means it fizzles, but success merely means Defender rolls against his skill. Defender does not apply a penalty to this roll based on Attacker's roll. From a mathematical standpoint, what's the effect of this? If the designers had decided to make it an opposed roll, and applied Attacker's margin of success as a penalty to Defender's defense roll, how would the game be different? The only thing I can think of is Defenders would fail more often - pretty much on par with the probability of standard opposed rolls as they currently stand. Did the designers remove the margin of success penalty to make the game less lethal? Has anybody applied the margin of success as a penalty, and how has that made your game run?