Bubble Bobble

On the start screen press: Down, up, down, up, right, down, left, down, up, down. A message will appear to signfy that the code has been entered correctly. When the message has come up, start a game as normal then, during play, press the following buttons:

R1: Skip to next level,
L1: Return to previous level,
R2: Bring up an options menu,
L2: Confirm selections on the options menu.