Alien³ [Model SNS-A3-USA]

Invincibility, unlimited weapons, and no damage codes:
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Begin the game and press ABYX on controller 2. Press A on controller 1 and a number will appear in the top corner. Re-enter the code on controller 2 and press B or X to increase the number to one of the ones below:

Code Effect
1 Invincibility
3 Invincibility
2 No damage
4 Unlimited weapons
5 Unlimited weapons and invincibility
6 Unlimited weapons and no damage

Level Passwords
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OVERGAME Ending
QUESTION Level 02
MASTERED Level 03
MOTORWAY Level 04
CABINETS Level 05
SQUIRREL Level 06

Various Cheats
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On Controller 2 press A - B - Y - X then enter the following code on Controller 1:
A - Invincibility
B - Double Damage Inflicted on Enemies
X - Infinite Ammo

Note: You can do all three of these cheats, but you will have to re-enter the code for Controller 2.