Press Left, Left, Right, Right, Right, Right, Right, Right, Right, Right, Left, Left, Left, Left, Left, Left, Right, Right, Left, Left, Left, Left, Left, Left, Left, Right, Right, Right, Right, Right, Right, Left, Left, Left, Left, Left, Left, Left, Left at the title screen, then select "Debug Game" at the screen that appears.
More Cheats, Achievements
