Successfully complete all objectives in the single mission dossiers. The following codes can now be enabled once you complete all objectives in the single mission dossiers
Invincibility:
Press Back and then press X(2) A B A during game play. A message will confirm correct code entry. Your first soldier will be invincible but the remaining members of your platoon can still be harmed. Note: You cannot complete the game normally when this code is active as maps and dossier items can no longer be unlocked.
Big Heads:
Press Back then press A X B Y A during game play. A message will confirm correct code entry.
Chicken Explosives:
Press Back then press X(2) Y A B during game play. A message will confirm correct code entry.
Paper Mode:
Press Back then press B A X Y A during game play. A message will confirm correct code entry. Characters will be two dimensional in this mode.
Slow Motion:
Press Back then and press Y(2) B X A during game play. A message will confirm correct code entry.
High Pitched Voices:
Press Back then press X A Y B X during game play. A message will confirm correct code entry.
