Black Mesa Incident

The Black Mesa Incident, or referred to once in-game as the Lambda Incident, was a catastrophic event resulting from an experiment carried out at the Black Mesa Research Facility that resulted in a Resonance Cascade. Its aftermath would see the invasion of multiple races of extra-terrestrials into Black Mesa; the resulting battle between the base personnel, human military forces and Xen creatures concluded in the complete destruction of the facility and almost all of its inhabitants; and, in the long term, attract the attention of the Combine Empire to Earth.

Cause
The Black Mesa Incident was caused directly by an experiment in Sector C Test Labs' C/33a Test Chamber. The experiment was supposed to analyze an extremely pure sample of Xen crystals, which various expedition teams had been collecting from the borderworld.

The GG-3883 sample was, in addition to being the purest, also the most unstable Sector C staff had experimented on. With the Administrator of Black Mesa keen to see positive results from the test, the Sector C staff decided to boost the Anti-Mass Spectrometer to 105% power, much higher than the equipment's safety buffer zone of below 90%, in a bid to garner better data. Eli Vance, one of the research leaders, argued against this decision but was overruled. Another scientist, Harold, warned his close friend Dr. Stanley Rosenberg about the danger of such energy boost. Just before the experiment, Rosenberg discussed the matter with fellow scientist Dr. Richard Keller, but Keller had no power to change the operating levels because the administrator insisted that the anti-mass spectrometer run at the levels he set for it.

Dr. Gina Cross and Dr. Colette Green were chosen to prepare everything for the experiment. While Dr. Cross delivered the sample to the testing chamber, Dr. Green powered the anti-mass spectrometer.

Such power drainage had strong effects on the entire facility. Elevators stopped, lights temporarily went out and some computers even blew up. The experiment was continued nonetheless.

Dr. Gordon Freeman was the scientist responsible for the insertion of the sample into the anti-mass spectrometer for analysis. As Freeman was preparing to do so, one of the overseeing scientists noticed a small discrepancy in the readings, but dismissed it as "within acceptable parameters". Upon receiving the sample, Freeman proceeded as ordered and inserted the sample. Immediately after the sample touched the machine's beam, a catastrophic resonance cascade began.

Immediate effects
The cascade had far reaching consequences. An expanding dimensional rift was brought into being, which caused extensive damage to the facility and summoned swarms of aliens to Black Mesa, teleported from the borderworld the crystals originated from. Thrust into an alien environment, these creatures were highly aggressive and attacked the Black Mesa personnel on sight, which soon resulted in heavy casualties among science and security personnel. Although the appearance and behaviour of these aliens seemed and was to a certain extent random, it swiftly became apparent that certain of the creatures were acting as one, less like confused animals and more like a determined military force, looking to establish a hold over their new environment.

Three survivors of the initial disaster, Dr. Gina Cross, Dr. Colette Green and Dr. Rosenberg, made their way to the surface and called in the military to help them with the alien onslaught. The military, in the form of the Hazardous Environment Combat Unit arrived quickly, bringing in troops, ordnance and vehicles via aircraft and trains. Aside from dispatching the aliens, these troops were also instructed to permanently silence the facility personnel. The HECU's foray into the facility was initially successful. They managed to establish control of Black Mesa's surface facilities and began to make inroads into its extensive underground, setting up several fortified outposts to keep the aliens at bay. They also managed to capture Dr. Rosenberg, who sent the distress signal, and locked him in a railway cargo car for interrogation.

While HECU established their presence in the underground, Dr. Green and Dr. Cross worked to prepare the satellite delivery rocket for launch, which was essential for the work of the prototype displacement beacon, a device capable of reducing the effects of the resonance cascade. Cross and Green first found a living security guard who knew the all-clear codes needed to lift the military air-traffic lockdown. The two doctors then entered those codes, successfully lifting the lockdown and allowing the rocket to be launched. However, the launch was aborted when soldiers captured the control room and massacred its personnel.

Barney Calhoun, a low-ranking security guard, managed to survive the initial events. Determined to escape the crumbling facility, he located and freed Dr. Rosenberg. With his aid, Rosenberg reached the old, abandoned A-17 Prototype Test Labs used for teleportation experiments. There, he hoped to use an old teleporter to escape from the facility. Calhoun helped the doctor first by travelling to Xen and activating a device necessary for successful teleportation, and then by finding and recharging a spare battery for the teleporter. Calhoun then narrowly escaped through the portal with Rosenberg and his two colleagues, Walter Bennett and Simmons, just as the HECU soldiers stormed the underground facility. While the doctors successfully reached the safe area outside of the Black Mesa, Calhoun was caught in a temporal harmonic reflux, travelling between Xen and the facility. However, he soon ended up together with the scientists and the four escaped in a SUV.

Escalation
The battle between the HECU troopers and the Xen invasion force escalated as the dimensional rift widened. The soldiers began to be pushed back as more aliens appeared, including the deadly likes of Alien Grunts and Gargantua. Heavy ordnance began to be utilized as the aliens spilled out onto the surface, in the form of upgunned M2 Bradleys, M1 Abrams main battle tanks, mortars, airstrikes and artillery bombardment. The facility turned into a confused and quickly deteriorating warzone. As the battle raged, Gordon Freeman, the scientist responsible for the original incident, became a top-priority target for the HECU, as he consistently avoided capture and overcame the military on many occasions in his attempts to halt the dimensional rift. He successfully launched the satellite delivery rocket prepared by Dr. Gina Cross and Dr. Collette Green. Afterwards, Dr. Cross and Dr. Green, with the assistance of Dr. Richard Keller, were able to manually raise, power and activate the displacement beacon for the prototype equipment, thus initiating a resonance reversal to help lessen the effects of the dimensional rift, although not aborting it permanently. During the beacon's activation, both Green and Cross were caught in a harmonic reflux, but survived and returned to the Black Mesa.

Shortly after this, Gordon Freeman was captured by HECU troopers. Instead of being taken for interrogation, he was dumped by two marines into a trash compactor. He narrowly escaped death and managed to work his way through residue processing areas before reaching the Lambda Complex, where the remaining members of the science team were holding out.

While Freeman progressed through the surface facilities, the conflict began to favor the Xen creatures, as heavy Xen weaponry and aircraft began to arrive, shooting down one of the reinforcement fleets carrying Corporal Adrian Shephard's squad. HECU soldiers found themselves overwhelmed, and with most of the original strikeforce slain those who remained fell back into the underground or began to evacuate, using airstrikes to cover their retreat. With the failure of the military force, the black operations contingent arrived, who set about killing any remaining human survivors and preparing a high-yield nuclear warhead to obliterate Black Mesa.

After the Black Ops' arrival, two Vortigaunts, R-4913 and X-8973, were successful in retrieving several stolen Xen crystals

Shortly after the evacuation began and the Black Ops troops arrived in full force, Freeman gained access to the Lambda Core complex. He was informed by one of the surviving scientists that the discovery had been made that the alien forces were being controlled by one super organism. Not only was this creature directing the entire invasion from Xen, it had taken control of the dimensional rift; as long as it remained alive, the invasion would continue and eventually consume the whole of Earth. The ragtag science team resolved to send Freeman to Xen via the Lambda teleporter in order to slay the super organism. The teleporter was destroyed by invading Xen aliens in the process.

Last hours
As the Black Ops assessed the situation via interrogation of captured HECU soldiers, a new and unknown foe appeared, the so-called Race X. One of the survivors of the HECU force, Corporal Adrian Shephard, managed to fight his way through swarms of the deadly aliens in a desperate attempt to find and escape from the infested base. Shephard and a few other surviving soldiers overcame several squads of the Black Ops soldiers, and managed to deactivate their warhead. Shephard then proceeded further into the facility and killed the Gene Worm, apparently ending the Race X threat.

Meanwhile, Gordon Freeman confronted the Nihilanth in Xen and succeeded in killing it. This action halted the Xen invasion, allowing the mysterious G-Man and his employers to temporarily take control of the borderworld. The G-Man reactivated the nuclear device, and detained both Gordon Freeman and Adrian Shephard at an unknown location and by unknown means. With the detonation of the warhead and the death of the Nihilanth, the Black Mesa Incident, as well as the facility itself, came to an end.

Aftermath
The consequences of the Black Mesa Incident were massive. The relatively small inter-dimensional rift caused portal storms to open all over the Earth, bringing large amounts of Xen wildlife to the planet and attracting the attention of the Combine Empire, which attacked and conquered Earth following a brief Seven Hour War. Dr. Wallace Breen, the former administrator of Black Mesa, was able to negotiate a surrender with the Combine on behalf of the human race, and as a result became puppet ruler of Earth. The death of the Nihilanth also ended the slavery of the Vortigaunt race, earning Gordon Freeman their eternal gratitude.

Although the incident is largely considered to have been a terrible accident, there is incidental evidence which suggests it was to some extent engineered. The Nihilanth seemed to have been planning the invasion from Xen for some time, and the G-Man has more than once hinted at his own manipulations of the affair, most notably when he whispered to Eli Vance just before the beginning of the resonance cascade to "prepare for unforeseen consequences". To what extent either of these individuals were involved in the authoring of the incident is not at this time known. Further dialogue at the end of Episode 2, in the chapter; "Our Mutual Fiend", suggests that the G-Man played some role in providing the Xen crystals to Black Mesa, and there is mention in the original game that The Administrator (Dr. Breen) went to great lengths to obtain the crystals, although it is unclear if he was aware how they would react during the experiment.

Known Survivors

 * Gordon Freeman
 * The G-Man
 * Barney Calhoun
 * Isaac Kleiner
 * Wallace Breen
 * Eli Vance
 * Alyx Vance
 * Doctor Rosenberg
 * Walter Bennett
 * Simmons
 * Adrian Shephard
 * Arne Magnusson
 * Unknown number of HECU and Black Op forces
 * Unknown number of Scientists and Security guards

Appearances

 * Half-Life: Day One
 * Half-Life
 * Half-Life: Uplink
 * Half-Life: Opposing Force
 * Half-Life: Blue Shift
 * Half-Life: Decay