Didn't the Tomb Raider reboot have that option? I think there was a trophy in there somewhere for making it through the game without killing anyone... I wouldn't know. I get kinda Manhunt-y when I get shot at. While we're on it, I liked Manhunt. It gave me the option to do to "someone" what I think about doing to that asshole that stops right in front of me for no reason when I'm walking to the gameshop.
I once heard a phrase that stuck with me: "A hammer thinks everything is a nail."
As a gamer I can find studies that'll say games do not induce violence. It's Marylin Manson/Ozzy/Judas Priest's fault. But as a metalhead I can find studies that say music isn't to blame either. As a mysanthrope I say it's other people. And the more of them together, the more violent thoughts I get. Put me in a movie theater and I'll be steaming just before the teasers are done.
I don't act on it though. That's what Manhunt's for. I think, at the end of the line, whatever the studies say, it's bad wiring. Me, I'm able to reason with myself and if nothing else, I can still restrain myself because I don't want to go to jail for giving the sudden-stopping-asshat what I think he deserves. But judging by a study that says domestic violence goes up during Superbowl, not everybody's prefrontal cortex is firing on all cylinders.
I'm not even saying bad wiring makes you an instant warlord. Hell, I have bad wiring, apparently I am on the edge of the autistic spectrum. But I know what is expected of me in a civilized world, so the parts I don't agree with I can still act my way through.
Err... I kinda lost my train of thought... Anyway, no. Games do not cause violence. It's probably chemtrails.