Primus principal Les Claypool has written the original theme track and four other themes for the Nintendo Wii "Mushroom Men" video games, due this fall.

This is the first game music for Claypool, who previously created the themes for TV's "South Park" and "Robot Chicken," as well as film scores. For Nintendo, it's believed the first time the leading game publisher will have original music from a top artist in one of its games.

The impetus to get Claypool came from Ryan Mattson, the game's creative lead at developer Gamecock Media Group. The company's CEO, Mike Wilson, was behind Trent Reznor's involvement in id Software's mammoth hit "Quake." A huge Claypool fan who built his own Les-style bass, Mattson thought the artist's style would be perfect for the game.

For Claypool, between his family's avid wild mushroom foraging near his West Sonoma County, Calif., home, and his son's obsession with fantasy gaming, it was an easy decision. "After seeing the design material and mock-ups online," he says, "I knew at once this was an opportunity to gain massive brownie points with my offspring, so thanks, 'Mushroom Men!'"

Nintendo's Wii "Mushroom Men: The Spore Wars," due Nov. 11, will have Claypool's original "The Mushroom Men" theme track with lyrics, and instrumentals for the game's four major themes, Morel, Bolete, Amanitas and Lepiota, all highly sought wild mushroom species. A companion Nintendo DS game, "Mushroom Men: The Rise of the Fungi," out Oct. 14, may use some of his instrumental music.

Gamecock and "Mushroom Men" are sponsoring Jam Cruise 7, which Claypool is headlining in January. Retail chain GameStop is doing a pre-order sweepstakes online for the Wii title, with the grand prize a trip for two on the Jam Cruise. The store is also giving away a Claypool "Mushroom Men" rock poster with pre-orders of the DS version.

Jam Cruise 7 promoter Cloud 9 will also run its own sweepstakes, with the top winner getting a custom "Mushroom Men" art bass guitar signed by Claypool.

All passengers will be able to play both "Mushroom Men" games and meet the creators on board, as well as have the opportunity to pick up copies of the game and get signed posters and games from Claypool and company.