I've been playing games since they began in the late 70's. A neighbour of mine had a Pac Man arcade machine in his garage and he'd let me play for free. So I've been a gamer for 30 years. Aside from bad eyesight and a being slightly withdrawn from society, gaming for all those years hasn't done me too much harm.
I've probably taken several millions of virtual lives in that time so I suppose you could say I am a Genocidal maniac! Most of the games I play do feature killing or death in some form. Even Pac Man had you killing or being killed. Why do we all like killing so much? Because it's fun. It's fun to kill people. I served for 10 years in the British Army but never killed anyone. I always wanted to have the chance. Would I hesitate? Would I feel remorse? Who knows. In the gaming world I kill relentlessly - friend or foe. The biggest rush I get is killing strangers online. When I 'pop a cap' in someones ass I can almost feel their anger as they re-spawn looking for vengeance only to be capped again as I hang around the spawn point. Yes, I'm that guy.
Last night I played Frontlines and killed the same guy 26 times in one round. I checked his stats afterwards and he was a pro gamer. He must've hated my guts and everytimes I nailed him I laughed my ass off. Am I sick? Probably. 30 years playing violent video games does make you a little nuts.