Castle of Illusion Starring Mickey Mouse (Sega,1990, MS). One of my favorite games ever - my Mario before I got to really play Mario. It is more similar to Capcom's DuckTales for the NES, but that was released just a year earlier so that seems to rule out a rip-off. Later on I also owned the Megadrive verion. That one looks stunning (although Mickey himself looks better in the MS version imo), but the gameplay of the 8-bit game outshines its 16-bit brother.