Donned with a special protective suit (the Hazardous Environment Suit, or HEV), Freeman must defend himself against not only alien invaders from another dimension, but also an elite detachment of United States Marine Corps soldiers (or robots in some versions of the game) sent to cover up the incident. Gordon Freeman, a theoretical physicist (and silent protagonist) who must navigate through a massive secretive complex (known as the Black Mesa Research Facility) after an experiment gone wrong. The first game from Valve, Half-Life puts players into the role of Dr. Half-Life is a sci-fi horror first-person shooter developed by Valve and published by Sierra for the PC on November 19, 1998.