Rayman was created for the PlayStation launch in September 1995. Ubi Soft will be developing a Rayman game very similar to the original. The game will make a return to the old-style 2D scrolling platform games of the 16-bit era and features levels based on those seen in the PlayStation version. Whether or not Rayman Advance will be released as a direct port of the PlayStation original remains to be seen, but in terms of size and scale, Rayman Advance is said to be huge, spanning across fifty or so levels.
The handheld edition is supposedly being developed with a two-player mode in mind via a link-up cable. A capture the flag option is being considered, but details of how this will work in a 2D environment have not been divulged.
Rayman for the GBA is scheduled for a 2001 release, but it is not known if it will launch with the console. Expect more details at E3 this May.