Quite a lot, I suspect - most of us have played computer games at some point, and we as a culture seem to find mass killing entertaining. The last game I played a lot was Civilization II. I tried to avoid war, but quite often found my population annihilated in nuclear holocausts (the game is rigged against peaceful, socialist economics). Perhaps the attraction is the safety-valve principle or it's a throwback to fighting off rival tribes and sabre-toothed tigers (we sure showed them).