At anytime during the game, press start to Pause and then enter any of the following codes. Each code can only be used once per game.
1,000 space credits: up,down,up,down,left,right,L,R,L,R,R,L
5,000 space credits: up,right,down,left,L,L,right,left,R,R,L,L
Pause the game and press Right, Left, Right, Left, L, R, Up, Up, R, R, L, L