Press C on controller two during game play.
Use the sound test selection on the options screen to play
sounds 1, 1, 9, and 2 (in that order). A round selection screen
Enter the options screen and set continues to "1",
difficulty to "Hard", ships to "2", and sound
to "65". Press A to begin game play.
Press C, A, C, A, Start,
B on controller two at the ship selection screen. A chime
will confirm correct code entry.
Start at level 2:
Hold B and press Start at the title screen.
Level 20 firepower:
Enter the options screen and set continues to "2",
difficulty to "Hard", ships to "3", and sound
to "77". Press B on controller two during game