To be honest I think the problem comes from the MMO playing. I used to be in a similar situation; played WoW for 10+ hours a day, cut off and abandoned my relationships with friends, and hardly ever spoke to my family. I was extremely lazy and didn't want a job, didn't care to get a license, etc. This type of addiction can have a HUGE effect on the personality of somebody, and it comes with many negative spillover costs....
If he ever quits playing and decides to actually do something with his life, you will see a massive change in him and he'll become much more approachable and open-minded when it comes to conversation. Playing an MMO or online game as extensive as I did is just a way to escape reality; you can be your own person. Outside that game it's pretty much a state of denial and they act like everything is fine, but it isn't.
My best advice is to wait it out until he can grow up and do something with his life. If he doesn't then that's his choice and, in my opinion, isn't worth keeping a relationship with.