Earthworm Jim: Special Edition is a version of the original game specifically designed for the Sega CD, an add-on device for Sega Genesis. The game not only comprises all levels from the original edition, but also provides additional sections along with an entirely new level known as "Big Bruty". It features a remixed CD audio soundtrack and roughly 1,000 extra animation frames. Unique to this edition are alternate endings that are triggered by winning on "Easy" or "Difficult" modes, featuring fanciful narration related to worms or bizarre player commendations respectively. Activision later ported the Special Edition to Windows 95.
The game's Special Edition was released for the Sega Genesis add-on, the Sega CD. It was based on the Genesis version, contained all of its levels, plus some extended section to the levels and a single completely new level, titled "Big Bruty", a new remixed CD audio soundtrack, as well as around 1,000 more frames of in-game animation. These versions were also the only ones to contain alternate endings when winning on the "Easy" or "Difficult" difficulties, in which a narrator rambles on about many (false) facts about worms or congratulates the player in a similar absurd manner respectively. The Special Edition was later ported to Windows 95 by Activision.