Earthworm Jim is a story about an ordinary average earthworm named Jim who goes about his normal daily life, cruising around avoiding crows and doing other general worm-like things. Until one day, Jim is suddenly struck by a very large Ultra-high-tech-indestructible-super-space-cyber-suit. Through sheer luck, Jim rests safely in the neck ring of the suit. Suddenly, the ultra-high-tech space particles of the suit begin interacting with Jim's soft wormy flesh. A radical light-speed evolution takes place. Jim soon realizes that he is now in control of the suit.
The gameplay of Earthworm Jim is similar to the first game, with Jim running and jumping through the levels. There are five new weapons to collect compared to the original game. Characters like Princess What's-Her-Name and Psy-Crow also appear in the game.