Start the game with the following parameters (QW.EXE -console)
then bring the console down by pressing ` (or ~ tilde) key and enter 
cheats below. 

God Mode - t_super_on / off 
Complete Mission - t_win 
Sniper Zoom Mode - smoothzoom_on / off 
Change Player Name - name new name 
Show Frame Rate - u fps_on / off 
Start Recording - u rec [filename] (record game) 
Start Record File - u replay [filename] 
Quit Game - exit