Press Y, X, B, X, A, X, L, R, A, X, A at the option screen. The screen will shake and the number "20" will appear below the "Options" selection to confirm correct code entry.
Level select
Press A, Y, A, Y, X, Y, B, A, R, L at the option screen. The screen will shake to confirm correct code entry. A level selection screen will appear.
Ten continues
Press B, A, Y, A, X, A at the option screen. The screen will shake to confirm correct code entry.
