Half-Life: Echoes

Echoes is set in the same location and time frame as that of Half-Life, taking place at a remote New Mexico laboratory called the Black Mesa Research Facility, showing the events of Half-Life from the perspective of a different protagonist. The player assumes the role of an unnamed character, referred to as "Candidate Twelve," a scientist.

An unnamed character, only referred as "Candidate Twelve," arrives for work at the Black Mesa Research Facility. The facility has flickering of lights and failing electrical equipment, with tremors shaking it as scientists begin to worry about the experiment. After entering a tram, the "resonance cascade" forces Candidate Twelve to fight for survival as the G-Man observes.[7][8][9][10][11]

After the resonance cascade, Candidate Twelve battles through the facility's sewer system, encountering other survivors along the way. The gargantua, a massive alien organism, stalks the player's movements. The player eventually escapes to the surface in a large freight elevator. At this time, military convoys can be seen entering Black Mesa. The player nearly escapes with a surviving security guard and scientist, but are ambushed by the HECU marines. Candidate Twelve escapes and battles the military en route back to the transit hub from the start of the game. Along the way, Candidate Twelve encounters visions projected by a sentient entity that grants visions of the Universal Union, also known as the Combine, from Half-life 2. The entity appears to be fleeing the powers of the enigmatic G-Man. Candidate Twelve arrives at a climactic confrontation between the Xen aliens and the HECU marines. After prevailing, the player is transported to the Black Mesa staff dormitories, where he is witness to the G-Man's rescue of Alyx Vance. The player is then abandoned by the G-Man and killed by the nuclear explosion from Half-life Opposing Force. Candidate Twelve's file is closed due to his influence from the mysterious entity from earlier in the game.