Hold 1 + 5 + 9 at the title screen. The word "Fight" will
confirm correct code entry. A turbo option will now be
accessible from the main menu.
Hold 1 + 2 + 3 + 7 + 9 + Option when the "Eye" appears
on the title screen.
Voice modem mode:
Press 9, 1, 1 at the title screen. The word "Awesome"
will confirm correct code entry.
Fight against Carbon:
Begin a game under "Hard" or "Killer" difficulty levels.
Win the "Earthquake Zone" stage with a double flawless
victory. This may be easily done by defeating the first
opponent in the game, then intentionally lose and continue
all other matches until the "Earthquake Zone" appears.
Then, hit your opponent once, then block until the time
runs out. l Carbon will appear in the "Subway Passage" stage.
Hidden Palace bonus level:
Press # at the background selection screen.
Subway Passage bonus level:
Press * at the background selection screen.
Set sound and music options:
Pause game play and press A, B, or C.