Located in the New Mexico desert in a decommissioned Cold War missile site, it is the former employer of Half-Life's theoretical physicist protagonist, Gordon Freeman, and a competitor of Aperture Science.

While the facility ostensibly conducts military-industrial research, its secret experiments into teleportation have caused it to make contact with the alien world of Xen, and its scientists covertly study its life-forms and materials.

After successfully destroying the tentacle with a rocket engine, in "Power Up", Freeman must kill a Gargantua alien by baiting it into a room with giant Tesla coils.

The warhead is later reactivated by the G-Man, and it detonates at the end of the game, destroying a significant portion of the facility and any survivors still trapped inside.

Black Mesa's themes of science and horror were partially inspired by "The Borderland", an episode of The Outer Limits that focused on a team of scientists who manipulated magnetic fields to enter the fourth dimension.

The path of the monorail itself is made up of six different map files without individual loading screens, adding hallways as transition areas to give the illusion of level streaming.

[5] The disaster sequence in the test chamber was created in a single weekend by developers John Guthrie and Kelly Bailey, who worked for 48 hours straight without sleep, ultimately exciting everyone in the office when they discovered and played it the following Monday.

Its visual design was called dystopian, featuring large amounts of solid-state hardware, much of which is malfunctioning or in disrepair even prior to the alien invasion.

[9] Scenes in Black Mesa have been described as "industrial disarray" and "bureaucracy run amok",[10] while the facility itself was called "an amalgam of every top-secret military-scientific installation ever created or imagined".