Blowing the brains out of some cybernetically-enhanced non-American in a video game might not have the same pysche-crushing effect as doing so in real life, but you don't know what's going on behind the scenes. Maybe that cluster of polygons resembling a human being had a virtual wife, and a small, pixelated child somewhere who will grow up fatherless, because some overpowered Main Character blasted everything in his path. But, hey! You know whose family won't miss them when you splatter their guts all over the pavement? Zombies.