In the real world:
Earthworm Jim is an anthropomorphic worm created(and originally voiced) by the insane genius Douglas TenNapel and marketed by Shiny Entertainment(of
MDK fame) and
Kids WB(who aired the cartoon). His first appearance was in the 1994
Sega Genesis(it was developed by Americans, so I used the American name) game of the same name, which recieved
unanimous acclaim due to its smooth animation, fluid controls, and crazy humor. It proved popular enough to warrant
ports to many other consoles of the time, and even made it onto the PC. Earthwom Jim's success even sparked a toy line and cartoon series(which included several gags from the game itself, most notably "cow launching"). The sequel, Earthworm Jim 2, had lower difficulty than the first game, and slightly modified controls, but was generally regarded as a worthy successor. Sadly, the Earthwom Jim franchise was killed in 1999 with the release of Earthwom Jim 3D(which was developed, not by Shiny Entertainment, but by
Interplay) - a mediocre, Super Mario 64-like game with the Earthwom Jim name. Jim's memory was
sullied even more in 2001 with the advent of the Game Boy Advance port - which, despite the superiority of the new platform to the original Genesis, had inexcusable flaws such as missing animation frames, poorly-tiled scenery, and
unresponsive controls. In 2007, a PSP remake of the original was developed, but never released(it was probably just as well, as it had absolutely none of the characteristics of the original). Earthworm Jim has also made cameos in
Interplay's semi-famous(or infamous) Clayfighter series. While he has a dedicated fanbase, Earthworm Jim is likely to remain unrevived.
In-universe:
The Insectican Queen, Queen Pulsating, Bloated, Festering, Sweaty, Pus-filled, Malformed, Slug-for-a-Butt(usually referred to without the adjectives), had her evil minions, Professor Monkey-for-a-Head and Psy-Crow, construct an "ultra high-tech, indestructible super-space-cyber-suit" that would give her the power to conquer the universe. However, on his way to delivering it to the Queen, Psy-Crow accidentally drops the suit out of his spaceship. It falls to Earth, and lands on Earthworm Jim, turning him into the famous hero. Queen Slug-for-a-Butt is determined to get the suit back, and sends Psy-Crow to retrieve it. Jim learns that the Queen is keeping her sister, Princess What's-Her-Name, locked in a dungeon, and is determined to
free her. Thus, the first game begins, with Jim progression toward Queen Slug-for-a-Butt's palace motivated by his obligation to free the princess, and Queen Slug-for-a-Butt's efforts to
quell him fueled by her determination to
reclaim the suit.