When you start the game press F1 and write: "cht_bEnable Cheats =" and if you write "cht_bEnable Cheats = 1;" (the ; is really important to write) you will unlock the principal cheats like give all weapons. but if you write "cht_bEnable Cheats = 2;" you will unlock the "Developer Cheats" (also when you start the game there will say: Developer Cheats Enabled) you can do the next: Press G to god mode Press O for all weapons and ammo Press I to become invisible to enemies Press K to kill all enemies Press J for Turbo Mode Press L for flying Press Y for ghost mode (you can go through Walls and doors)