When I was a kid, we played "Cowboys and Indians" with plastic guns every day.
I never grew up and shot any real Indians? So I'm finding the video game excuse pretty fucking lame.
Some spoiled brat, head case of an adult, was having a temper tantrum because he didn't get his own way, so he murdered his mother and 26 innocent, defenseless people, including 20 children. Stop calling it anything but that.