Cause more damage:
To cause more damage to enemies, pause the game and hold L2, then press L1, L1, R1; next, release L2, hold down R2, and push the following: R1, R1, L1. To disable it, enter it a second time.

God mode:
To activate God mode, first pause the game. Hold L2, and press square, triangle, triangle, square; next, release L2, hold R2, and press triangle, square, square, triangle. To disable it, enter it a second time.

Unlock all campaign missions and planes:
To unlock all campaign mission and planes, at the main menu, hold L2 + R2, and press square, L1, R1, triangle(2), R1, L1, square.

Unlock Vampire MK1:
To unlock Vampire MK1, you must first unlock the Vampire during game play. Then, at the main menu hold L2 + R2 and press L1(2), triangle(2), square, L1.