Contra Cheats for GameBoy

Press Up(2), Down(2), Left, Right, Left, Right, B, A, B, A, Start at the title screen.

Press Up(4), Down(4), Left(4), Right(4), Start at the title screen. Alternately, pause game play and press Up(2), Down(2), Left, Right, Left, Right, A, B, A, B, Select, Start.

Press Up, Down, Left, Right, A, B, Start at the title screen.

Enter B32R as a password.

Enter H2F2 as a password, then press Start to advance to the next level.