Sound test: Insert a second controller and disconnect the Zapper.
Hold Up/Left + B + A on controller two at
the player selection screen. The sound test menu should appear.
Press A + B to exit.
Hidden message: Successfully complete the game three times. Press
A on controller two when the word "Congratulations"
appears.
Alternate ending sequences: Destroy the enemy hideout four times in a row. Note:
When the game ends with a second player it also will differ.
