Just bought Rock Star of my 17 yr. old for his birthday, he and his friends love it. They play it every day, sounds like I have a herd of buffalo above me. I thank the Lord I never broke down and bought and actual drum kit.
My youngest just turned 12 as well, he got a unicycle. He loves anything with wheels. It’s kept him quite busy, he is determined to ride it.
If he's the type of kid who likes challenges...and you have a couple trees in your lawn or in a park, buy him a slackline sometime.
My kid's in college, but when he was about that age we bought him a slackline and he and his college aged friends, will still string it up in the yard or at a park and play with it. I think it's the challenge of mastering it, plus it's a good "core" exercise in that it challenges your balance.