Hi. My son's diagnosis. officially is Pervasive Developmental Disorder (PDD)-not otherwise specified, although he is definitely higher functioning. The videogame obsession is normal for a child on the spectrum. One of the symptoms is "narrow interests." I have to force my son to do sports, take bike rides, and go to summer school so that he gets involved in other things. He never wants to go, but he always enjoys himself once he's out.
Other than psychiatric care is he seeing somebody who understands Pervasive Developmental Disorder (PDD) kids and can help you help him? Often they treat kids on the autism spectrum as if they have psychiatric problems and from what I've seen that just doesn't work. These kids need interventions specific to their own disorder...not medications, talk therapy (most don't communicate well) or behavioral therapy (never worked for us). Teaching my son social skills, forcing him (yes FORCING) him to do certain activities that he was good at and learning how to go easy on the transitions was very helpful and he is now doing well. What didn't work was seeing a psychiatrist as his primary doctor, medication, and concentrating on behavior rather than helping him learn more about functioning in a world he didn't understand. These kids have trouble cooperating. They are not "bad" kids. They have a terrible time with transitioning and see all people as equal...teachers, kids, parents...they desperately need text book teaching on social skills and you won't get that from a psychiatrist. Most psychiatrist do not understand autistic spectrum disorder.
These kids are very sensitive and can perceive the slightest correct as "yelling at me." My son, who is sixteen, almost seventeen" will break into tears and cry about "I'm stupid" "I'm an idiot" if we so much as tell him that we caught him sitting down with the dog instead of walking him so could he please walk the dog around the block (this recently happened). Two days has gone by and he is still mumbling "I'm so stupid." This is not mental illness. This is autistic spectrum disorder. We are still working hard on his oversensitivity, but from an autism standpoint.
You may want to talk to somebody from the Autism Society for suggestions on what kind of services he needs. You can see that traditional psychiatry is not helping him. I'm not surprised. That didn't help my son either because, although he acted different than other kids, he was not mentally ill. In fact, treating him as if he were only made things worse and more desperate...good luck, whatever you decide to do.