Michael Jackson was meant to write the game music for Sonic 3 on Megadrive/Genesis. His music ended up being scrapped and somebody else was called in to do it, but much of the music either strongly resembles or contains passages resembling parts of songs MJ has written. One of the really obvious ones is Carnival Night Zone, there's a short motif just before the music starts to loop from the beginning again, which is note for note identical to a motif from a song MJ released as a single some time ago (can't remember the name, sorry). Interestingly, the tracks which feature these resemblances were replaced in the PC version of the game.
http://www.youtube.com/watch?v=JbVM-l2Oku4
Short video about this, although they suggest MJ was still responsible for at least some of the music.