I haven't done this, just thinking about how I would handle this...we did go through a 4 year period of not having t.v. or video games..but this was before my boy was big enough to crave those things...just putting that out there to say that I have guided a family through living without t.v. and games..
well, to ease this, I would work really hard to keep him busy and engaged with other things, which will be a lot of work for you, but long term- in a few months he hopefully will become able to entertain himself, this would be your long term goal. If he really has a problem, and it sounds like it, if he has turned down other fun to finish levels, then I really think you are going to have to work hard to help him.
when he gets home from school, start off with a snack and sit and visit, ask about his day. Then, have some kind of activity planned...bake something together, do a craft, go for a walk...go throw a ball in the yard or ride a bike together. Go to the library. Listen to a book on tape, we love books on tape here, Hank the Cowdog is hilarious, your boy would love that series, check your library, they might have it. Artemis Fowl is another a boy would enjoy. Go to the bookstore. We go at least once a week, get a hot chocolate and my boy looks at comics, like calvin & Hobbes.
The key is to keep him busy. When you do need moments to get something done...get out some watercolors and have him paint.
it will be a lot of work for you, but it will pay off in the long run. I know you feel bad about how deep it got, I can see that in your post, but I do think you deserve a pat on the back that your boy was able to come to you and talk to you about it, and look to you for help.