Don't talk to him... even as friends.
Leave him to his video games for a while, and before you know it, he'll come crawling back prepared to listen to some reason!
He gets agitated when you speak to him while he's playing, because reality is intruding on his fantasy. Therefore speaking to him each day isn't allowing him the chance to miss you - on the contrary, it's making him quite complacent. It means he's being left to his fantasy, and has you as a safety net in reality.
He doesn't consider you gone... he considers you there, but leaving him alone.
You're right where he wants you.
Don't be that person. Endure the pain it takes to leave, and set up your life as if he's not coming back [of course, he will...] but live your life as if he won't.
He'll come back because the pain of loss [which he's not experiencing at the moment... as I said, he still considers you 'there'] will intrude on his fantasy the same way you do when you try to speak to him.
Give him a month or two to experience this pain, don't take it as an insult if he's not bidding for your heart immediately. Remember: he's lost in his own little world, it's going to be hard for him to find his way out, but eventually, he'll basically be BEGGING you to help him.
He'll fast apologize for what a prick he's been, when he's finally forced to look at the shitful reality he created around him!