Garry’s Mod is a sandbox mod for the Source Engine. Unlike normal games there aren't any predefined aims or goals. Players are given tools and are left to entertain themselves. The player is in a world where objects can be created and destroyed on demand. Where people can be created and destroyed with the click of a mouse. A world made for him. A world he made.
After the Battle of City 15, the Combine found themselves in a dilemma, they were unable to revive their offensive against the human factions of the alliance and the Consortium as they both began to retake the territories the Combine had conquered at the beginning of the war and the Overwatch were spread thin along a wide front on all dimensions.
To help relieve some pressure off the Overwatch, the Combine began to pull Civil Protection Units from the cities and putting them through basic training after extensive brainwashing. The Combine called these units "Civil Protection Combat Operators" or CPCOs.
The main purpose of this unit was to take the place of Overwatch units in secondary duties such as purging infected from combine-controlled areas, occupation forces, recon, protection of important combine officials(I.E Collaborators, governors of territories), and hunting of RED and BLU Spies, so those Overwatch units could be use on the Frontlines.
The CPCOs worked, the Combine began being able to hold their territories more effectively, although it was already too late to regain the momentum the Combine once had.
However the CPCOs had a few serious defects that effected their strategic effectiveness: They were unable to fight the forces of the Alliance and the Consortium in open combat due to their lack of access to heavy weaponry, which made them useless as offensive units and despite the brainwashing programs, the CPCOs were prone to enemy infiltration.
Also if captured by Alliance or Consortium forces, CPCOs usually faced execution since they were widely viewed to them as traitors to humanity.