SINGLE PLAYER MODE :
       
                   The first thing you have to do is enable the Cheats.
                  

                  
                       -Press ~ to go to console. 
                       -Type /spdevmap [Mapname***].
                       -Now you'll automaticly begin a Single player game
                        and cheats are enabled .

                   Type the following commands in console.


                        Toggle God mode                    /god
                        Toggle no clipping mode            /noclip                                  
                        All weapons and ammo               /give all                                              
                        All levels unlocked at skill 1     /iamacheater                               
                        All levels unlocked at skill 100   /iamamonkey                                 
                        Spawn indicated item               /give [Item Name]                     
                        Hidden Sarge skin                  /model sarge/krusade