Add 1 credit per each hour on game play
After 18 hours game play

Game play hour is cumulative. It counts when you actually play the game. It does not count when you just wait on the title and demo screens.

You can check your game play hours on the Load/Save option.

It saves your game play hour when:

1.) You gameover.
2.) You reset the game by software reset.
3.) You goto the Pause Menu and exit to the title.

Press Start to the Pause Menu and then enter the code.

Full power up cheat is cumulative. After you use one, it deducts from the total.

For example:

At the beginning (stage 1), you have only 1 full power up cheat.

At stage 3, if you never use it, you have 3 full power up cheats.

At stage 5, you have 5 full power up cheats, etc.
Up, up, down, down, left, right, left, right, L2, R2

Gives you 1 Speed Up, Missile, Double, 4 Options & ? (Force Field)
Up, up, down, down, left, right, left, right, L1, R1

Gives you 1 Speed Up, Missile, Laser, 4 Options & ? (Force Field)