Press Up(2), Down(2), Left, Right, Left, Right, B, A at the title screen. Then, press Start to begin the game in single player mode or Select + Start to begin in two player mode.

Press Up(2), Down(2), Left, Right, Left, Right, B, A before the demonstration begins at the title screen. Then, press Start to begin the game in single player mode or Select + Start to begin in two player mode.

Press Up, Down, Up, Down, Left, Right, Left, Right, A, B, A, B, Select, Start when "Jungle" appears on the demonstration screen.

Begin game play in two player mode. Press A + B when losing a life to use a life from the other player.

Press Down(2), Up(2), Right, Left, Right, Left, A + B before the demonstration begins at the title screen.

Press Up(2), Down(2), Left, Right, Left, Right, B, A, Start(2) at the main menu.

Hold B + A and press Start at the title screen to display the sound test screen to hear the game's sound effects and music.

Crouch on controller one and press Up on controller two in the Base 1 or 2 levels.

Successfully complete the game and start another game. The new game will feature the same amount of lives at the end of the last game and more difficult opponents.