Level select
 
 At the main menu, select either one or two players and press Circle
 (instead of X) to begin the game. Then a selection screen that allows
 any level, including planet Mercury with a new power-up and an "Alien
 World" featuring the best background in the game will appear.
 
 Classic mode and credits
 
 Enable the "Level select" code, choose level 00, and complete it to
 unlock an ending, classic mode, and credits. Press Right when
 selecting then number of players to access classic mode. Enter the
 options screen to access the credits. 
 
 Nine lives
 
 Pause the game and quickly press Right(3), Down, Circle, Left, Down.
 
 Five shots
 
 Pause the game and quickly press Down, Left, Circle, Down, Right(3).
 
 Game Shark Codez:
 
 
 Joker Command P1
 D00E0C8C ????
 
 Joker Command P2
 D00E0CAC ????
 
 Infinite Lives P1
 800EF6C8 FF63
 
 Invisibility P1
 800EF6C0 004A
 
 Max Score P1
 D00EF6CC 0000
 800EF6CC FFFF
 
 Infinite Lives P2
 800EF794 FF63
 
 Invisibility P2
 800EF78C 004A
 
 Max Score P2
 D00EF798 0000
 800EF798 FFFF
 
 Extra Life (Both Players)
 8005DB30 0001
 
 Infinite Lives (Both Players) 
 8005DB3A 2400
 
 Infinite Continue Time
 8003DF36 2400