18 is too high. I would say 16 is fine even 15. I've been playing shooters since I was around 8, almost 30 now and I've never killed anyone. It's about how you raise your child, teach them right from wrong. Are they mentally ill? Are they depressed? There are so many determining factors as to why a person does what they do. Edit: Truthfully I think Facebook is more dangerous to a child's mental health than a fantasy shooter with next to no elements of gore. Sure you can shoot a head off a knight but you don't see brains come busting out and blood dripping everywhere. I've seen way more violence on Facebook with people burning puppies, people jumping other people because of color. Hell the news has more of an impact for children, that's where they see real violence.