Kudos to derf, who pointed out an interesting article on violence that, among other things, actually cites Marathon 2 as a potential source of violent responses from college students. Must be all those BOB incidents... the relevant excerpt:

In another study cited by the authors, college students who played the violent video game Marathon 2 generated 43% more aggressive responses in later tests than those who played a nonviolent game.

Two things need to be pointed out here. First, Marathon is a computer game, not a video game. These people obviously didn't research! Scandalous! Second, 43%? 4 + 3 = ...