V.W.
I'm not positive, but my kids have been playing it for over a year. There are different modes and some you can get killed and some you can't. And there are different servers. My kids usually hook up on one server with their friends and so it is their friends in the game with them (I don't know if there are others or not, but they work together with their friends, not steal from each other).
My kids are 11 & 14. All their friends seem to play it, too.