At the main menu type 'fifthdimension'. 
 Then use the following codes while playing the game: 
 
 F1 - Return to normal 
 F2 - Enlarge paddle 
 F3 - Single gun 
 F4 - Double gun 
 F5 - Missile gun 
 F6 - Laser 
 F7 - Clear level 
 F8 - Suicide