Cheat mode:
Highlight the "Options" selection at the main menu, then hold A + B on controller two, then hold any button (but not the D-pad) on controller one. Keep all buttons held until additional options that allow level selection, new difficulty levels (Mania and Very Easy), and increasing number of lives up to nine appear.

Two players as same character:
Hold Down/Right + B on controller one and Left + A on controller two at the title screen. Press C on controller two while all buttons are held. Select two player mode and choose the same character. Note: Both characters will appear identical.

Two players as same character (European version):
Hold Right + B on controller one and Left + A on controller two at the title screen. Press C on controller two while all buttons are held. Select two player mode and choose the same character. Note: Both characters will appear identical.

Bonus life locations:

At the very start of stage 1, move to the bottom left of the screen and press B.

In the first scene of stage 1, if a player defeats Altet (the second opponent that appears from a manhole), he/she will get extra points and may earn an extra life.

In stage 2, after leaving the supply truck, go back in, move to the top, and press B.

In the alien house, stage 3, defeat Dehelits then search in the bushes at the bottom of the screen for an extra life.

Reveal cheat menu code:
Successfully complete the game under the hardest difficulty. The game will reveal the cheat code during the last picture of the ending credits.

Hint: Stage 6: Kill one Boss only:
In stage 6, with the 2 bosses, defeat Souther (the Boss with claws) and Stealth (the other Boss) will die as well.

Hint: Max: Slam:
Play as Max, then try to hold somebody. Press C (the person might fall off) and while you are in the air, immediately press B to do a slam. If you hold the person backwards and do it, it will be more effective because he slams the person on the knee.

Hint: Surviving throws:
When you are thrown by an enemy, hold Up and hold C (Jump) to land safely. Note: You will not land safely when you are flung off an edge --you will still take damage.