Press Triangle, Down, Up, Triangle at the "Push Start button" screen. An icon will appear in the top right corner of the screen to confirm correct code entry. Select puzzle mode or arcade mode to access additional levels.
Secret characters
Press Triangle, Up, Down, Triangle at the "Push Start button" screen. An icon will appear in the top left corner of the screen to confirm correct code entry. Weepy and Smiley will be unlocked in all modes except for story mode.