Quickly press Left, Up, Right, Up, Left(3), Right, Down(2) at the title screen. The sound of a boom will confirm correct code entry. Note: The code must be entered before the high score screen appears. Press R during game play to get nine credits.
Level skip
Enable the "Unlimited continues" code. When the high score screen appears, press Right, Up(2), Left, Right(3), Left, Down(2), Right, Up. The sound of a boom will confirm correct code entry. Press L during game play to jump to the next level.