I find this a very interesting subject, and agree wholeheartedly that too much video gaming is not good. I have brought up three children in this era of video gaming and my personal experience is that it is related to the personality of each child, as well as parenting. My eldest was desperate to have a playstation (at that time the one) and received it for her seventh or eighth birthday. She was allowed two hours at the weekend, that she could administrate herself. We had the odd argument over "more time" etc, but she knew the rules. As she got older she continued to enjoy it and still does at 26, but does not play obsessively, from what I understand. It is occasional.
My boy (now 19) was a nightmare with the games until he was about 17, it was really difficult to ensure he did not play obsessively and he got into trouble more than once for getting up after he was presumed asleep to play! (he got caught because of the racket he made when playing, shouting at other players on this online game!!!) He is now much more into his music (he plays base) and he spends most of his waking hours practising - thankfully, he plays quite well, or I would have committed suicide by now!
The youngest is now 10 and has no video console (her brother has one in his room, but she has no interest) She sometimes visits a friend who loves to play, but she negotiates with him in advance, how long they will play video games, as she doesn't enjoy playing for hours and then they play other things.
As for the OP, I agree with trying to learn something about his game, even maybe get a second hand xbox (if that is the console he likes) to have at your house, but there he has time limits and does other things - that way you have the lure to get him to your house and can control how long he uses it when he is with you, which might also, longterm, help him to control how long he plays, if that makes sense.
Seems to me, if you cant beat em, join em - but with a level of control over the time devoted to gaming.