Alright these are both VIDEO GAMES but hear me out here they are entirely music related.
www.playauditorium.com
This one is kind of a puzzle game. You increase the size of these circles to direct waves of light. The light affects a percentage, sort of, of how much of the game's music plays. It's kind of, uh, inspiring? In a way. Hard to explain.
www.balldroppings.com
I don't know if you would even call this a video game, it is more of a strange, experimental music making tool, hence the reason I'm posting this here and not on Non-Sonics. Basically balls start dropping on a black screen. You draw lines with your mouse and depending on how you do it, the music will change pitch and tone or whatever. Play around with it, it will at the very least amuse you.