Various Codes
On the cheats menu, enter the following codes:
Invincibility - SQUARE, SQUARE, X, TRIANGLE, X, CIRCLE, X, CIRCLE
Unlimited ammo - X, TRIANGLE, TRIANGLE, TRIANGLE, X, CIRCLE, X, SQUARE
All future weapons - X, X, X, TRIANGLE, CIRCLE, CIRCLE, SQUARE, X
All past weapons - CIRCLE, CIRCLE, TRIANGLE, SQUARE, X, TRIANGLE, TRIANGLE, SQUARE
Quadrupled damage - TRIANGLE, TRIANGLE, TRIANGLE, TRIANGLE, SQUARE, X, CIRCLE, SQUARE
Automatically complete missions - SQUARE, SQUARE, TRIANGLE, CIRCLE, CIRCLE, X, SQUARE, TRIANGLE
Fight TX Endoskeleton in every battle - TRIANGLE, SQUARE, TRIANGLE, X, TRIANGLE, TRIANGLE, TRIANGLE, TRIANGLE
50% more health in combat with TX - TRIANGLE, TRIANGLE, SQUARE, X, CIRCLE, TRIANGLE, SQUARE, CIRCLE
50% more health for TX in combat - SQUARE, TRIANGLE, SQUARE, TRIANGLE, CIRCLE, X, CIRCLE, X
Unlock All Levels
On the cheats menu, press SQUARE, SQUARE, SQUARE, CIRCLE, CIRCLE, CIRCLE, TRIANGLE, TRIANGLE.
Centipede Mini-game
Press Circle, Circle, Circle, Square, Square, Square, Triangle, Square at the code entry screen. Alternately, successfully complete the game to unlock Centipede at the 'Atari Games' menu. If it is not unlocked as soon as you complete the game, restart your PlayStation2, reload your game, and recheck the 'Atari Games' menu.
Missile Command Mini-game
Press Circle, Circle, Circle, Square, Square, Square, X, X at the code entry screen. Alternately, in the vet's office on level 13, walk into the small office on the far right side. Approach the computer and press X to play Missile Command. Then, successfully complete the level to unlock the game at the 'Atari Games' menu.
All FMV Sequences
Press Triangle, Circle, Square, X, X, X, Triangle, Circle at the code entry screen.
All Still Pictures
Press X, Square, X, Square, Circle, Triangle, Circle, Triangle at the code entry screen.
View Development Team
Press Circle, Circle, Circle, Square, Square, Square, Triangle, X at the code entry screen.
Hint: Best Weapon
The best weapon to destroy the machines is the Tec-Com Plasma Gun. It has a second fire that is an exploding plasma cannon.