Audio Surf

There's a game called Audio Surf and it's a puzzle racing music adapter game. Basically, it takes a song you want to listen to, gives you a car, and puts tons of obstacles in your path depending on the beat of the song. The amount, consistency, and difficulty of the drops depends entirely on the song. The best part of this is, it can be ANY song you want. It literally places everything on the fly as the song plays, it's really awesome.