Pro Action Replay Codes:
Infinite Health - 00C7EE:03 -Rune
Infinite Lives - 00C7EC:03 -Rune
Shoot One Invader To Clear Round - 00C846:01 -Datel
Faster Shooting - 00C7E7:02 -Rid
Makes You Invisible - 00C7E6:01 -Rid
Faster Shooting Improvement Code [Note 1] - 00C7E9:22 -Rid
Note 1: Used with above code makes one of your bullets stick to the top of the screen so you can always hit the flying saucer.

Game Genie Codes:
Start with 2 lives - 02A-E1C-E66 -Galoob
Start with 5 lives - 05A-E1C-E66 -Galoob
Start with 7 lives - 07A-E1C-E66 -Galoob
Infinite lives - 00F-D5B-3BE -Galoob
Start with 3 shields - 02B-09E-E66 -Galoob
Start with 6 shields - 05B-09E-E66 -Galoob
Start with 8 shields - 07B-09E-E66 -Galoob
Infinite shields--except when stomped - 007-43E-E6E -Galoob