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

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

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

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.

Ace Killer:
To unlock Ace Killer, defeat all of the other Aces.

Ace of Aces:
To unlock Ace of Aces, get the highest score in all Campaign missions.