DS4 has been playing computer games since 2. Like others, we allow, but don't encourage. When I need to do my work, I get priority.

There are so many great free games online now - we have found good ones on smart-kit.com (site created by a neurologist), which led us to jayisgames.com, a site that holds competitions for all those smarties creating games (and they're all available to play). As a prize for taking his IQ test, DS4 chose a JumpStart World computer game for 2nd grade. I don't know how great that is, but he really wanted it for some reason and likes it.
One (sort of) useful thing: I think withholding computer is the only thing that works for a consequence right now - DS4 doesn't care about other things. I'm thinking the long MN winter is contributing to this computer use. Once it's nice outside, we won't be able to get him in.