Press ` while playing the game. Then, enter one of the following codes, watch out, some codes might be case-sensitive:
Effect - Code
Loaded - All Explosives, Full Ammo, etc.
Ghost - No Clipping Mode
Fly - Fly Mode
TheMatulaakLives - God Mode
Walk - Walk Mode
Invisible 1/0 - Invisibility (On/Off)
Behindview 1/0 - 3rd Person View (On/Off)
FreeCamera 1/0 - 3rd Person View (On/Off)
Teleport - Teleport to Reticle
HOG - Massive Damage to Reticle
Fierfek - All Ammo
Darman - Skip Mission
AllWeapons - All Weapons
DeafEnemies 1/0 - Enemies Don't Hear You (On/Off)
BlindEnemies 1/0 - Enemies Don't See You (On/Off)
DeafAI 1/0 - Deaf AI (On/Off)
BlindAI 1/0 - Blind AI (On/Off)
SmiteEvil - Destroy All Enemies in Radius
KillPawns - Kill Squad Mates
Slomo # - Set Slow Motion
SetJumpz # - Set Jump Force
SetGravity # - Set Gravity
SetSpeed # - Set Speed
FreezeFrame # - FreezeFrame (After # seconds)
Changesize # - Scale Player's Size
Stat FPS - Show FPS
Stat Game - Show Game Stats
Suicide - Suicide
ViewBot - Cycle Through Bots
ViewSelf - Reset Camera to Player
LockCamera - Lock Camera