I know people don’t like giving gift certificates, but they really are appreciated and he can get what he wants.
For video games, Skyrim is a great choice if he doesn’t have it.
When I was about that age, I loved going to Putt-Putt for Mini-golf and playing the arcade games. So a fun gift might be $50 worth of arcade tokens. Or if you are near one see if it is possible to gift him a pass to Six Flags or equivalent.
If you are only going to see him on Christmas this won’t work, but if you live near him, offer to treat him to an upscale restaurant (ideally without his parents).
We used to go to the arcade because the games were better than our console games. Now the games on our consoles are better than the games at the arcade unless you are talking about the simulator games where the game is moving you.