Jelly Boy is a platform game that exists as a prototype for the Sega Genesis. Prototype games often have incomplete features, unfinished graphics, or glitches.  It's likely that the gameplay would involve guiding Jelly Boy through various levels, overcoming obstacles, and potentially collecting items.  Due to its prototype status, complete details about its gameplay and intended features are unavailable to the general public.

Jelly Boy (Europe) (Proto)

Janou Touryuumon (Japan)