Cheat Codes:

Go to ID4's Main Menu and enter one of the following names under "Player Name".

LIVE FREE - INVINCIBLE
TOURIST - SELECT LEVEL
GO POSTAL - DAMAGE BONUS, WEAPONS, FAST RELOAD
FOX ROX - SELECT LEVEL
GODZILLA - KILL CIVIL, KILL WING
MR HAPPY - SELECT PLANE
KYRA NR - SELECT LEVEL, SELECT PLANE INVINCIBLE, KILL CIVIL, KILL WING,
DAMAGE BONUS, WEAPONS, FAST RELOAD
BRENDAN QR - SELECT LEVEL, SELECT PLANE, INVINCIBLE, KILL CIVIL, KILL WING,
DAMAGE BONUS, WEAPONS, FAST RELOAD
DOOFUS - SELECT LEVEL, SELECT PLANE, INVINCIBLE, KILL CIVIL, KILL WING,
DAMAGE BONUS, WEAPONS, FAST RELOAD
GREG FM - EVERYTHING
SCOTTYWAR - EVERYTHING
ROSA DUONG - EVERYTHING
KIWI - SELECT LEVEL, SELECT PLANE, INVINCIBLE, WEAPONS, FAST RELOAD COCO - EVERYTHING
RADARMY - EVERYTHING
DAB DAB - EVERYTHING
TRI S - EVERYTHING

Now exit back to the Main Menu and press CTRL, RIGHT SHIFT, 8 (at the same time)... BINGO! The Cheat Menu.