Psh, my parents were letting me play these when i was 6. Anyways, CoD games are on the less violent side of rated M video games (online at least). It's really only basic shooting with a very little amount of blood, nothing profane or explicitly brutal.
what ever and why are you looking at my comments that is kinda creapy
It's not creepy at all. I have no idea who you are or what you're like so giving an opinion based on nothing would be stupid. Plus your spammy/curse/MW3 obsessed comments are littered all over the Tavern and I just clicked the last post on 5 of them to find some by you.
They should be
It depends on the person. I have a younger brother who is 11 and a younger sister who is 9, and I would not let him play something like Cod if it was left to me unless I or some other adult figure was around to keep him in check, he's hyper-active, immature, swears a lot and angers quickly. I would however have no problem with my sister playing it whenever if she wanted to because she is mature enough to handle it.