checked-no =>Sound Test: On the title screen, press R L D U. =>Secret Options: In the Sound Test, play sounds 7 4 3 7 4 8 1, pressing <1> to play each sound. A secret options menu will appear, allowing you to change the difficulties, adjust controls, or play the game as a jet. =>Continue: On the Game Over screen, press U U D D L R L R D U D U. The game will then continue. This can be done up to nine times. =>Secret Contest Screen: If you manage to fill the entire high score table with the initials ERI, you'll get a special screen telling you about a contest Sega was running when the game was originally released. =>View Final Enemy: Hold L on the title screen to view the final enemy of the game. =>Unlimited Lives: On the Name Entry screen after you die, enter X eleven times. You should now have unlimited lives on your next attempt.