Invincibility:
     Pause the game and press B, L, B, R, Y, L, X, Down.

Bullet shield:
     Pause the game and press B, B, R, L, Y, X.

Cheat codes:
     Enter these codes at the Enigma Machine.

Code:                   Result: 
BALLOWAX                Unlock Everything 
EAGLE                   Unlock Mission 2, A Storm in the Port 
HAWK                    Unlock Mission 3, Needle in a Haystack 
PARROT                  Unlock Mission 4, Several Bridges Too Far 
DOVE                    Unlock Mission 5, Rolling Thunder 
TOUCAN                  Unlock Mission 6, The Horten's Nest 
SEAGULL                 Get a Gold Medal on the current mission 
SILVERSHOT              Silver bullet, One hit kills enemies 
FLAWLESS                Perfectionist, One hit kills you 
BOUNCE                  Rubber grenades 
REFLECTOR               Bullet shield 
HIDENSEEK               Invisible Enemies 
MADHATTER               Men With Hats 
BIGBOOMER               MOHton Torpedo 
SUPERSHOT               Snipe-O-Rama, all weapons are sniper mode 
HEADSUP                 Achilles' head, Enemies only dies of headshot

Get the EA LA Medal of Valor:
     Finish with a Gold Star in every mission.

Understand the Germans:
     Turn  on  the subtutles in the Options menu to undertand what the
Germans are saying.