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
Combinations of these grid squares can give different Alien effects.
There are other combinations for large, small, and variable colors.
The eggs and face huggers do not always show up immediately, however
pressing [Start] brings up the effects.
6 + 13: Clear red aliens, eggs, and face huggers (normal size)
6 + 7 + 12 + 13: Clear yellow aliens, eggs, and huggers, and greenish-yellow
guardian aliens (normal size)
5 + 7 + 12 + 14: Clear teal aliens, eggs, and huggers, and bluish
guard aliens (normal size)
5 + 6 + 7 + 12 + 13 + 14: Clear green aliens, eggs, and huggers
(normal size)
All tiles: Large green everything