Press ~ during game play to display the console window, then type 
sv_cheats 1 to enable cheat mode. Then, enter one of the following
codes at the console window.
Note: Cheat codes cannot be enabled during in offline practice. 

Effect                        Code
---------------------------------------------
God mode                      asw_god 1
Full ammo and all weapons     asw_gimme_ammo
Full health                   asw_gimme_health
Disable auto-reload           asw_auto_reload 0
Enable The Director           asw_horde_override 1
360 controller support        exec 360_controller_pc.cfg
First person view             firstperson
Level tile-based generator    asw_tilegen
Server browser                openserverbrowser