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.
Jim is a normal earthworm, until a special "super suit" falls from the sky and allows him to operate much like a human, with his "worm-part" acting as a head and the suit acting as arms, body, and legs. Jim's task is two-fold, he must evade the game's many antagonists, who are after him because they want the suit back, and also rescue and protect Princess What's-Her-Name from them. The game plays out with Jim eluding and defeating all enemies, and saving Princess What's-Her-Name. However, not only does she not return Jim's affection, but she is also crushed by the flying cow that was launched at the beginning of the game by Jim himself.
