yeah- if the game is for MATURE people, then, heck, you should be Mature and able to understand that the game is fake and not to go arround killing people because the guy in the game did.
I for one play Halo a lot, but no, I don't think it affects me at all. However, for young kids, like Some Guy said, it will screw up their minds
Live the life you love, love the life you live