Free play mode
 
 At the "Press Start" screen, hold L1 + L2 + R1 + R2 and press Start.
 While still holding L1 + L2 + R1 + R2, press Up(7), Down, Up(4),
 Start. If you entered the code correctly, the phrase "Limiter
 released" will be spoken. Go to the configuration screen and turn off
 the credit limit to enable free play mode. Alternatively, play the
 game a total of two hundred times. 
 
 Level select
 
 Complete arcade mode on the combat mode difficulty setting. Enter the
 configuration screen to access the new selection.
 
 Thirteen ships mode
 
 Complete extra mode on the combat mode difficulty setting. Enter the
 configuration screen to access the new selection.
 
 Shooting down rate
 
 Complete arcade or extra mode on the thirteen ships mode difficulty
 setting. Enter the configuration screen to access the new selection.
 -From: Olikong@aol.com
 
 Extra credits (Japanese version)
 
 At the title screen, repeatedly tap Select to set the total credits
 to nine. 
 
  Game Shark Codez:
 
                    
  Infinite Lives P1      
  800D784C 0009
                    
  Infinite Missiles P1   
  800D7878 0000
                    
  Infinite SP Attacks P1 
  800D787A 1000