Press Up five times before the Aztec Adventure scroll opens on the title screen. Press Right three times while Nino tosses money at the other characters. Press Left, Down while all characters are walking toward the left side of the screen. Nino's face will appear next to the Aztec Adventure scroll to confirm correct code entry. Use the D-pad to change the level numbers appearing below the face.
Sound Test
Start the game, and at the screen with the rainbow, press Left once, then Right twenty times. Nino's face will appear to the right of the rainbow to confirm correct code entry. Use the D-pad to change the numbers appearing above the face to select a sound, then press 1. To resume game play, select sound 00 and press 2.