Various cheats
     Run  game,  enable console from options menu. Press ~ to bring up
console.  Type  "seta  thereisacow 1337" and then "spdevmap " or go to
the  map  you  want  from the menu, but it will not work if you resume
game.

For mapname, put the name of the map you want to load with cheats 

Type the following options you want in the console: 

Cheat code:         Effect:
give all            Access All Weapons
god                 God Mode
noclip              No Clipping Mode
notarget            Enemies Ignore You
give ammo           Full Ammo
jump_height #       Adjust Gravity (Default = 39)
timescale #         Adjust Time (Default = 1.00)
cg_LaserForceOn 1   Add Laser Sight to All Weapons
cg_drawGun          Remove Gun
cg_fov              Zoom with Any Gun
give rpg            Give RPG
give g3             Give G3
give mp5            Give MP5
give dragunov       Give DRAGUNOV
give beretta        Give BERETTA


Various cheats (DEMO VERSION)
     Enable the console from the game's in-game options. Hit the tilde
key (~) to drop the dev-console. Type seta thereisacow "1337" and then
press ENTER. Type spdevmap bog_a and then press ENTER. This will start
the  demo with cheats enabled. When playing, drop down the dev-console
and  enter  the  following  codes  and hit ENTER to activate or toggle
them.

Cheat code:         Effect:
give all            Access All Weapons
god                 God Mode
noclip              No Clipping Mode
notarget            Enemies Ignore You
give ammo           Full Ammo
jump_height #       Adjust Gravity (Default = 39)
timescale #         Adjust Time (Default = 1.00)
cg_LaserForceOn 1   Add Laser Sight to All Weapon


Unlock Arcade Mode and Cheats Option 
     After  completing  the  game,  these  options  are  automatically
awarded to you.

Unlockable:              How to Unlock:
Arcade Mode              Complete the game on any difficulty. 
Cheats Menu              Complete the game on any difficulty.