A.R.C.

A.R.C. The A.R.C. logo.

General Abbreviation Anomaly. Research. Center. Allies Eagle Detector Enemies A.M.T.F.

The A.R.C is the main research group studying the anomalies occurring inside of gm_construct 13 beta. They have built a small base of operations in the map for closer and more direct observation, albeit not immune to the effects of some anomalies.
There is also an additional base on the "gm_building_construct" map and a message from them can be found in "gm_kitchen_remaster."