Cheat mode
Enter "ROCKSTAR" as a name. Press [Start] to pause game play and enable the "Invulnerability" option. Press [Left] or [Right] at the mission selection screen to choose any mission and phase.

Destroying trucks
When shooting at trucks, shoot the front. Next, go to the side and place one charge. Then, run away and the truck will explode.

Difficulty settings
The programmers have the difficulties mixed up in the "Options" screen. Easy mode is supposed to be "Private", normal mode "Corporal" and hard mode "Sergeant". However, if you choose "Sergeant" you will get a much easier difficulty level. To set the difficulty correctly, use the following steps.

Easy: Go to "Options" and set the difficulty to "Sergeant".
Normal: Go to "Options" and set the difficulty to "Corporal".
Hard: Go to "Options" and set the difficulty to "Private".

Full health
Pause the game, then hold L1 + L2 + R1 + R2 and press Triangle(2), X(2).

Full ammunition
Pause the game, then hold L1 + L2 + R1 + R2 and press X(2), Triangle(2).

First special weapon
Pause the game, then hold L1 + L2 + R1 + R2 and press Triangle, X(3).

Second special weapon
Pause the game, then hold L1 + L2 + R1 + R2 and press X(3), Triangle.

Heavy weapon
Pause the game, then hold L1 + L2 + R1 + R2 and press Triangle, X, Square(2).

Level select
Pause the game, then hold L1 + L2 + R1 + R2 and press Triangle, Circle, Square(2).

Level skip
Pause the game, then hold L1 + L2 + R1 + R2 and press Circle, Square, X(2).

Invincibility
Pause the game, then hold L1 + L2 + R1 + R2 and press X, Triangle, Square, Circle.

Infinite ammunition
Pause the game, then hold L1 + L2 + R1 + R2 and press Circle, Square, Triangle, X.

Rocket boots
Pause the game, then hold L1 + L2 + R1 + R2 and press Triangle, Square(2), Triangle.

Jet pack
Pause the game, then hold L1 + L2 + R1 + R2 and press Square(2), Triangle(2).

All crates powered-up
Pause the game, then hold L1 + L2 + R1 + R2 and press Circle, X(2), Circle.

Instant shape build
Pause the game, then hold L1 + L2 + R1 + R2 and press Square(2), Circle(2).

Indestructible base
Pause the game, then hold L1 + L2 + R1 + R2 and press X, Triangle(2), X.

Easy gun build
Pause the game, then hold L1 + L2 + R1 + R2 and press Circle(2), X(2).

Easy buddy build
Pause the game, then hold L1 + L2 + R1 + R2 and press Circle(2), X, Circle.

Animals do not attack
Pause the game, then hold L1 + L2 + R1 + R2 and press Circle, Square(2), Circle.

Big feet
Pause the game, then hold L1 + L2 + R1 + R2 and press Triangle, Square(2), X.

Big guns
Pause the game, then hold L1 + L2 + R1 + R2 and press Triangle, Circle(2), Triangle.