Enter the following as your character name, and then hit 1 for a 1 player game, or 2 for a 2 player game.

Password - Effect

GUMMI1 - Skip to level 1
GUMMI2 - Skip to level 2
GUMMI3 - Skip to level 3
GUMMI4 - Skip to level 4
GUMMI5 - Skip to level 5
GUMMI6 - Skip to level 6