I agree with those who've commented on imposing limits on older teenagers. They're near adults. They really need to be self-limiting now.
Ok, here's some anecdotal evidence that has no bearing on any of your lives:
As kids, my younger brother and I were not allowed to watch ITV (poor quality programming apparently, plus too many toy adverts!!!) only BBC. We were limited to an hour of TV after school. We never had a games console (ok we had a second hand Spectrum at one point but my brother took it apart and reprogrammed it
)
My younger sister and brother who came after us, had no such limitations on their TV watching, plus they had unfettered access to a Playstation, including Zombie shooting games such as Resident Evil.
It made, and continues to make no difference in our lives as children or adults. We still played out, read, studied etc as much as each other.
I really think it is possible to make too big a deal out if it all. It's not the "Nice, middle-class children" who are read to, given books, taken to places of cultural interest, and have responsive, responsible parents, that will suffer from exposure to video games, even violent ones. It's the kids who come from backgrounds of social poverty, whose parents neglect their needs, who never have an adult intervene in their play, who are left to their own devices for hours every night; that really suffer from exposure to video games.
I see them every day at my school. They're 8 years old and have a TV and Xbox in their room, but haven't been north of the Thames before (I live in zone 2, south London). No one imposes a bedtime on them. They get up and take themselves to school. No one collects them. They walk home through Brixton alone, and spend the evening plugged in to Call of Duty. 