Hi A. d.,
we've signed ours up for three programming classes over the summer. Two are through Oakland university and the other is a sleepover camp at University of Michigan. Mine plays video games too (I judge you NOT!) :-) but he wanted to get a little more hard core into the actual programming piece of it, rather than just game design. Check with your local community college and/or local universities. They offer these "camps" and your kids don't have to enroll or audit or anything like that.
the one at U of M is through IDtech camp. Google that and see if they offer one at a university near you. He went with a buddy last year and they had a blast.
let the pocket protectors fly free!!! LOL. good luck and have fun!! S.