Alien Resurrection Codes -

Cheat mode:
Press Circle, Left, Right, Circle, Up, R2 at the main menu. A "Cheat" selection will appear on the options screen, allowing God mode, all weapons and unlimited ammunition, unlimited oxygen, no chestbursting, and level selection.

Research mode:
Press Square, Up, Down, Circle, Left, R1 at the main menu. A "Research Mode" selection will appear on the options screen. This mode allows you to change some of the game's Aliens and Facehuggers (shrinking them, making them wire-framed, semi-transparent, etc.). This is done by highlighting various grid squares as follows.

1: Small aliens
2: Quarter-size aliens
3: Tiny aliens
4: Half-size aliens
5: See-through green aliens
6: See-through red aliens
7: Invincible aliens
8: Tiny face-huggers
9: Large eggs
10: Hard enemies
11: Very hard aliens
12: Faster aliens
13: Red eggs and face-huggers
14: Slow aliens
15: Faster, weaker aliens
16: Faster, weaker face-huggers