Buster Fight © 1994 Sega Enterprises, Limited.
* Additional Difficulty Levels and Characters: At the title screen, enter the sequence Up,Down,Left,Right,Down,Up to unlock the Extra Level (harder than Hard Level) and the boss The Alien. Enter the sequence Up,Up,Down,Down,Left,Right to unlock the Zero Level (easier than Easy Level) and the boss The Alien. In both cases, a sound will confirm if the code has been entered correctly.
Alternatively, Zero Level and the boss The Alien can be unlocked by getting an high score and entering KEY as initials.