Extra levels: Press L, Up, R, Down at
the title screen. A creature will appear in the bottom right of
the screen to confirm correct code entry. Select puzzle mode,
then choose the new "Another World" option. Alternately,
press A, Up, B, Down at the title
screen.
Play as Bub: Press Z + L + R + A at
the game selection screen.
Level skip: Press Z + L + R + A during
game play.
Bonus characters: Select "Puzzle Mode". Then, press Left(2),
Up, Down, L, R, L, R,
L + R at the puzzle selection screen. Bub, Bob,
and the Boss characters may be selected. Alternately, press Left(2),
Up, Down, Left, Right, Left,
Right, L + R at the puzzle selection screen.
