Start game as usual. During gameplay press (~) TILDE to go to console, 
then enter the following cheats followed by ENTER: 

GIFTFROMPTERODON - Enable Access To The Following Cheat Codes: 
CHTHEAL - Restore Health 
CHTHEALTEAM - Restore Health For Team 
CHTWEAP (X) - Get Weapon Where X Is Value 0-30 
CHTAMMO - Refill Ammunition 
CHTGRENADES - Get Grenades 
CHTALLQF - Access Quickfights 
CHT3PV (0/1) - Play In 3rd Person View 
SHOWFPS (0/1) - Show FPS Information 
SHOWPROF (0/1) - Show Other Statistics 
CHTCANNIBALS - Enemies wear masks
CHTKOSTEJ - Enemies don't do damage