The
Half-Life series begins in the 2000s, at the fictional
Black Mesa Research Facility in
New Mexico.
Dr. Gordon Freeman, a recently employed
theoretical physicist, is involved in an experiment analyzing an unknown crystalline artifact; however, when the spectrometer beam contacts the crystal, it opens a dimensional rift between Black Mesa and another universe, causing aliens to swarm Black Mesa and kill much of the facility's personnel. Attempts by the Black Mesa personnel to close the rift are unsuccessful, leading to a specialist
US Marines unit being sent in to silence the facility, including any survivors from the science team. Freeman fights through the facility to meet with several other scientists, who decide to travel to the alien dimension,
Xen, to stop the aliens. On Xen, Freeman eliminates the alien "leader" and is confronted by the
G-Man, who offers Freeman employment before putting him into
stasis.
[1] Back in Black Mesa, a second alien race begins an invasion, but are stopped when a Marine corporal,
Adrian Shephard, collapses their portal into the facility. The G-Man then destroys Black Mesa with a nuclear warhead, and detains Shephard in stasis.
