Selene fighter
 
 Beat the game on the hard difficulty level without using any
 continues. After the ending credits, save the game to a memory card,
 then start a new game. Now at the fighter selection screen, cycle
 through the ships, and there will be a Unknown Fighter Type II called
 the Selene. This new ship can carry 9999 rounds of ammo for any
 weapon in the game. -From: dj7672@mc2k.com 
 
 Extra fighters
 
 Unlock fifteen or more secrets and beat the game on any difficulty
 level to fly in one of the small Earth fighters. Beat the game on the
 hard difficulty level without continuing more than two times to fly
 in one of the Moon fighters from the final level.
 
 Extra option
 
 Beat the game with a high ranking to access a "Gallery" option from
 the main menu. Select it to view various graphics depicting the
 ships, weapons, and battles in the game.
 
 Start with gunpods
 
 Begin a game and reach a point where various gunpods have already been
 obtained. Then, intentionally lose the game and use all remaining
 lives. Allow the timer to reach zero on the continue screen. Allow
 the title screen to reappear and select "Game Start". Now select a
 ship and equip it as desired with the gunpods that are now available.
 The selected gunpods will also reappear automatically as a standard
 weapon after a life is lost during the next game.
 
  Game Shark Codez:
 
       
  Joker Command                                     
  D0083E2C ????
       
  Invincible                                        
  80085718 00A5
       
  Infinite Lives                                    
  800813C4 0003
       
  Infinite Special Weapon Ammo                      
  80084832 000F
  80084834 000F
       
  Unlock Gallery with All Pictures                  
  801FEC9C FFFF
  801FEC9E FFFF
       
  Score Multiplier Always at 40                     
  80081326 0028
       
  Press Triangle to Refill Ammo to ???? (0001-9999) 
  D0083E2C 0010
  80084832 ????
  80084834 ????
       
  Endymion MK. 2                                    
       
  Press Triangle to Get ? Weapon                    
  D0083E2C 0010
  80085734 0?00
       
  Astrea                                            
       
  Press Triangle to Get ? Weapon                    
  D0083E2C 0010
  80085734 0C0?
       
  Infinite Top Pod Ammo [Note 1]                    
  80084982 000F
       
  Have Unknown Fighter Type I [Note 2]              
  D0083E2C 0010
  80081434 0003
       
  Have Unknown Fighter Type II [Note 2]             
  D0083E2C 0010
  80081434 0004
       
  Quantity Digits to Accompany Weapon Modifier Code 
       
  1 - Vulcan                                        
  2 - Wasp                                          
  3 - Grenade                                       
  4 - Cannon                                        
  5 - Blade                                         
  6 - Hedgehog                                      
  7 - Spreader                                      
  8 - Riot                                          
  9 - Flash                                         
  A - Python                                        
  B - Mosquito                                      
  C - Juno                                          
       
 Note 1: Always use the infinite ammo code with the weapon select code.
 
 Note 2: At the fighter select screen, press Triangle.