Reach the following levels in the game to unlock the corresponding character in Multi-Player mode:

Unlock Gale:
Reach Level 45.

Unlock NEVEC:
Reach Level 55.

Unlock Stranger:
Reach Level 30.

Unlock Hero:
Reach Level 75.

Press A + X instead of just X to be able to throw the anchor a bit further.

Enter the following codes during Single Player Campaign mode to unlock the corresponding effect. To enter the codes just pause the game and enter them. These codes will only work on Easy mode and the current level that you are on and must be entered again after each level to activate them. If the code has been entered correctly you will hear a sound as confirmation.

Unlock Infinite Ammunition:
Enter: RT, RB, Y, X, Right, Down, Left, LB, LT, RT, RB, Y, X, Right, Down, Left, LB, LT, RT, LT, LB, RB, Y, Left, Down, X, RB + LB.

Infinite Health:
Down(3), Up, Y, Up, Y, Up, Y, Up(3), Down, X, Down, X, Down, X, Left, Y, Right, X, Left, Y, Right, X, RB + LB (Heat will still go down).

Unlock 500 Thermal Energy:
Enter Up(2), Down(2), Left, Right, Left, Right, X, Y, RB + LB.

Enter B, A, X, Y, B, A, X, Y, B, A, X, Y when a cut scene is being played.

Complete the game on either Easy, Normal or Hard difficulty setting.

When you level up the following costumes and characters become unlocked.

Basic Costumes - Level 01

3rd Pattern for Basics - Level 10

4th Pattern for Basics - Level 20

Stranger Character - Level 30

3rd Pattern for Stranger - Level 35

4th Pattern for Stranger - Level 40

Gale Character - Level 45

3rd Pattern for Gale - Level 50

NEVEC Character - Level 55

4th Pattern for Gale - Level 60

3rd Pattern for NEVEC - Level 65

4th Pattern for NEVEC - Level 70

Hero Character - Level 75

3rd Pattern for Hero - Level 80

4th Pattern for Hero - Level 85