Port Overdosed: This is the game in the Rayman series with the most ports. To put this into perspective, this was a launch title for both the Nintendo DSand its sucsessor the Nintendo 3DS. Not to mention an an iPhone version, a Game Boy Color version, and even a PS2 remake. And that's not even counting the two PlayStation Network versions (one being a port of the PS1 version, the other being a port of the PS2 remake)!
What Could Have Been: Rayman 2 was originally going to be a 2D sidescroller like the first game, and a playable Beta version can be found in the Playstation port.