Earthworm Jim 3D borrows much of its gameplay from other platformers of the era, notably Banjo-Kazooie and Super Mario 64. New locations in Jim's brain are opened up by collecting Golden Udders, and new levels in each location are opened by collecting Jim's marbles. Like previous Earthworm Jim games, despite many platforming elements, Jim's primary method of combat comes from shooting his Blaster. Jim is hit by a flying cow that sends him into a coma. Jim awakens within his own mind and discovers he has gone insane. His past villains have entered his mind and if something doesn't happen soon, Jim will be in the coma forever. His super ego has been unleashed within his mind to stop the madness. To restore his sanity he must find the golden udders of lucidity.