Cheats for Alien: Resurrection on PS1.
At the main menu press one of the following button combinations to unlock the corresponding menu:
Circle, Left, Right, Circle, Up, R2.
Unlocks the Cheat Menu in the Options menu.
The Cheat Menu includes: Level selector; Infinite ammo; Infinite health; No chestburst; No drown.
Square, Up, Down, Circle, Left, R1.
Unlocks the Research Menu in the Options menu.
The Research menu is a grid of squares that you can light up in any order/pattern you wish. Doing so will alter the appearance of the aliens you encounter in-game.