Unlock the 13-Ship Mode setting in Option menu under Configuration by completing Extra Mode. To enable this mode, change your ship stock until you get to 13. You can also change the order of the ships under a special setting when 13-Ship Mode is enabled. Note that you can only use one credit in 13-Ship Mode.
Complete Arcade Mode or Extra Mode on any difficulty to unlock the Stage Select feature under Configuration in the Option menu. Toggle the Stage Select setting ON if you want to pick any stage in the game or OFF to play the normal game.
STAGE SELECT - HOW TO UNLOCK Stage Select (Arcade) - Complete Arcade Mode regardless of difficulty and credits used Stage Select (Extra) - Complete Extra Mode regardless of difficulty and credits used
Set the game to 13 ships in the configuration screen, then complete the game in arcade or extra mode to unlock the Shooting Down Rate option in the configuration screen. When enabled, the game will display the number enemies destroyed during game play.
When the phrase "Press Start" appears at the opening screen, hold L1 + L2 + R1 + R2 and press START . While still holding L1 + L2 + R1 + R2 press UP(7), DOWN, UP(4), START. The phrase "Limiter released" will be spoken to confirm correct code entry. Enter the configuration screen and turn off the credit limit to enable free play mode, or play the game a total of two hundred times.