X-Files: Resist or Serve At code screen enter any of the following cheats: Invincible: Up Square, Circle, X, Down. Infinite Ammo: L1, L2, X, R2, R1 All Acts: R2, Right, L2, Up, Square. One-Shot Kills: Circle, L2, Down, R1, X. All Bonus Features: Left, R1, L1, Down, Circle. Grenade Bullets: X, Circle, Square, L2, R2.