Cheat Codes
Press ~ to bring up the cheat console. Type "giftfrompterodon" to activate the cheat mode. Then type one of the phrases below to activate that cheat:

Enemies don't do damage: chtkostej
Enemies wear masks: chtcannibals
Get grenades: chtgrenades
Quickfights: chtallqf
Refill ammo: chtammo
Restore health: chtheal
Restore health (team): chthealteam
Weapon select: chtweap (0-30)
Out of body experience: cht3pv (0/1)
Display framerate: showfps (0/1)
Display system stats: showprof (0/1)