From outside, it is difficult to give any specific advice. The main question here is what do you mean exactly when you say “he spends so much time playing that he has no time for you”—is it the case that he really never has time to talk to you, or is it rather that he does have time, but not as much as you would like?
As a gamer married to a gamer, I can tell you that there is pretty much nothing as frustrating as someone trying to hog your attention when you are trying to play, except for trying to talk to someone when they are playing and cannot spare the attention. ;)
Solution is do not try to do both at the same time. Talk to him about it, and agree with him that when he is playing, you will let him play and not pester him on MSN, if in turn he will concentrate on talking to you when you two are spending time together (online or otherwise).
Several things can happen after that agreement.
The best outcome is that you both become happier, because you will actually concentrate on each other when you talk to each other, and he will get some quality gaming time when he does not need to feel guilty about not responding to you, and you will not feel bad about him not responding to you right now if he is busy, because you know there’s going to be another “date” soon. (Yes, you can actually have “online dates”, agreed times when you talk to each other for an hour or couple of hours, share news and links and so forth. I highly recommend that instead of expecting each other to respond all the time.)
A possible bad outcome is that you find that he will spend all his time gaming, and not dedicate any to you. This would probably speak of a “gaming addiction” (which I do not think is a real addiction, but a problem with his life being less appealing than the games, or a problem of self-control, but that’s beside the point), in which case, he being so young, I would actually suggest you express your worry to his parents or any friends of his you know who live close to him.
Another possible less optimal outcome is that he will give you some of his time, but not enough for to make you happy. This would speak of an incompatibility between you two, and you would then have to decide if you can be happy with that sort of relationship, or if you wish to move on.
Despite the possibility of less than happy outcomes, I would argue that you still want to talk to him and try and arrive an an agreement of time usage, because if he has a gaming problem or if there is an incompatibility, you will want to know now, so you can draw your conclusions and act from an informed basis.
EDITed to add: “made you” close your Twitter account? How exactly did he make you, and from the other side of the country too?