Disclaimer: I realize that a lot of folks (including many professionals) think having autistic kids play games is moving them in the wrong direction (away from social interaction). The friend below, who has both personal and professional experience in this, does think so. And I'd argue that if you can just shift an autistic child toward more social games (without increasing game time) would have little downside. And some folks feel that you should work on your strengths not your weaknesses.
A friend of my runs an Autistm center and has an autistic 5th grader. I've noticed that he really craves social approval (he loves performing for an audience). But a lot of social interactions are just a bit too overwhelming to him while at the same time inscrutable (reading facial expressions).
So I was thinking that a video game (which he loves) where the interaction is rewarded (teams do better than individuals, etc.) but where that interaction is very explicit (chat instead of face to face conversations) might be a good "stepping stone" for him: Interaction that's not overwhelming but also easy to digest (more "literal").
He has access to a Wii, 3DS, and also internet on computer.