Select Level
Pause play by pressing START. Then, hold Z and press R, B, A, B, A, C-Up, C-Down, C-Left, C-Right, C-Up, C-Down, C-Left, C-Right. Correct code entry is confirmed with a sound. Enable the new "Unlock Worlds" option that appears to select any level.

Get Extra Levels
Pause play by pressing START. Then, hold Z and press C-Down, L, R, L, R, L, R, L, R, L, R .Go to the "Enter Secret Worlds" option and press A to play the new levels