HADES

HADES is a rogue artificial intelligence (AI) that was formerly a subordinate function of the AI GAIA serving as the "extinction failsafe protocol" for Project Zero Dawn, and the main antagonist of Horizon Zero Dawn.

Purpose
HADES was one of a suite of nine subordinate functions under the control of GAIA as part of Project Zero Dawn. The criminal hacker Travis Tate was the lead programmer in charge of HADES’ development. If GAIA's terraforming efforts proved unsuccessful with regard to producing an environment suitable for sustaining life, HADES' function was to reverse the work done, reverting the planet to its previous lifeless, sterile state so that GAIA could engage in another attempt. In the process, any life that was introduced during the terraforming attempt would be exterminated. As such, HADES was not a true AI, but could instead be considered an extension of GAIA.

HADES' last resort failsafe function intrinsically meant that it only acted if required. Since GAIA's first terraforming attempt was successful, HADES was never required, and thus remained inactive.

The Signal
Nearly 1,000 years after GAIA went online, a signal of unknown origin was transmitted to GAIA Prime, the facility where GAIA was located.

The signal unshackled GAIA's nine subordinate functions, including HADES, turning them into highly advanced, very powerful AIs. HADES sought to reverse GAIA's terraforming efforts and restoration of life to the planet, even though they had been successful. To do so, it attempted to seize control of the terraforming system from GAIA. Unable to fend HADES off, GAIA resorted to self-destructing by overloading the GAIA Prime fusion reactor in an effort to destroy HADES. However, HADES released a virus that destroyed the coding that bound it and the other subordinate functions to the facility, and thus escaped the facility before it was destroyed.

Sylens
HADES found refuge in the still-functional computer core of the remains of an FAS-BOR7 Horus deep in the jungles of The Jewel, southwest of the Carja capital Meridian.

Trapped and unable to move or interact with the environment, HADES began broadcasting a signal in the hope that someone would detect it and come to its aid. In the technologically primitive new world it found itself in, this would have been highly unlikely. However, the signal was indeed detected by a wandering maverick Banuk named Sylens. A self-styled researcher, Sylens had a deep obsession with the knowledge and technology of the humans of the old world, referred to as the Old Ones. Years of finding and interacting with Old One technology from exploration of various ruins of their civilization had given him extensive experience with, and understanding of, their technology, starting with his discovery and use of a Focus. Indeed, it was his Focus that detected HADES' signal. Tracking the signal, Sylens found the helpless AI, and used his experience and understanding to repair the computer core housing it to the point where it could communicate verbally.

The Spire
HADES questioned Sylens about the world; its tribes, politics and points of interest. Sylens supplied the information, familiarizing HADES with the new world.

However, there was one point of interest HADES wanted to know about above all else. This was the Spire, a towering, monument-like structure that was clearly of old world origin, close to Meridian, the capital of the tribe that controlled the land in which it was situated: the Carja. The Spire was in fact one of a global network of transmission towers built by MINERVA, another of GAIA's subordinate functions. MINERVA had used the towers to broadcast the shut-down codes for the Faro Plague worldwide after GAIA brute-forced them. HADES intended to use this network to broadcast a signal that would reactivate the robots. It would then allow them to obliterate the biosphere as they did before, exterminating all life in the new world and again leaving the Earth sterile. Thus its goal would be achieved.

The Eclipse
However, in order to get to the Spire, the surrounding lands had to be brought under its control. Realizing the potential usefulness of Sylens to that end, HADES promised Sylens all the old world knowledge he desired in exchange for his service.

Sylens readily agreed. HADES first had Sylens recover and repair as many Focuses as he could find and establish a communications network for them. Sylens did so, recovering, repairing and networking several dozen of the devices.

HADES next sought to build an army that would, at his bidding, conquer the Carja, securing the Spire for its use. Sylens suggested forming a warrior cult from the losing faction of the Carja tribe's civil war, called the Shadow Carja. He proposed that HADES pose as a deity from their religion, the Buried Shadow, in order to induce the two key Shadow Carja leaders, the High Priest Bahavas and the kestrel commander Helis, into forming the cult. HADES agreed, and Sylens arranged an encounter between the two men and the AI. The meeting had the desired effect; believing HADES to be the Buried Shadow, who would help the Shadow Carja defeat the other faction and retake Meridian, the men formed a cult of priests and warriors, the Eclipse, in service to HADES. Thus HADES had its army, equipped with the Focus network that it had Sylens set up. To bolster their power, it also had them exhume several Faro Plague robots, which came to be known by all who saw or encountered them as Corruptors and Deathbringers. Once its army was formed and equipped, HADES decided that Sylens had outlived his usefulness and transmitted an instruction to Helis to detain and kill him. The wily Sylens, however, had secretly built a back door into the network, and was thus able to monitor communications without HADES of the Eclipse knowing. He heard the transmission and escaped. However, he continued to monitor HADES and the Eclipse.

Aloy
As part of their intelligence gathering in preparation for their assault on Meridian, the Eclipse pressed a scout and scrounger named Olin, of the Oseram tribe, into their service by abducting his family and threatening to kill them. They equipped him with a Focus and placed him in Meridian, with HADES and the Eclipse constantly monitoring everything he saw and did. However, he was selected to be part of a delegation sent to the territory of another tribe, the Nora, to promote peace between the Carja and the Nora in the aftermath of previous strife, and to observe the Nora ceremony commencing the rite of passage of their youth as new Braves, called the Proving. It was at this ceremony that Olin encountered Aloy, a young female participant in the Proving.

Upon seeing Aloy, HADES noted that she was wearing a Focus, which meant that she had at least a cursory knowledge of Old One technology. This was disconcerting. But what alarmed the AI was her appearance; she bore a striking resemblance to GAIA's creator, a renowned Old One scientist named Dr. Elisabet Sobeck. The resemblance was far too great to be mere coincidence, and indeed it was not. Aloy has been created by GAIA using genetic material from the long-deceased Sobeck, as an agent with the ability to access sealed Zero Dawn facilities anywhere and acquire the resources to eventually rebuild and reboot GAIA. But more importantly, with regard to HADES, she could access the control room in the ruins of GAIA Prime and retrieve the one thing that could stop it: the terraforming system's master override. Only Elisabet Sobeck had the authorization to activate the override via her genetic fingerprint. Since Aloy was her genetic clone, she would have the same fingerprint, and therefore would also be able to activate the override, which had the power to purge HADES. Thus correctly surmising that her existence was an extreme threat, HADES immediately ordered an attack by the Eclipse on the Proving to kill her.

But though she was almost killed by Helis, she survived. After learning, from a Focus lost by one of the Eclipse she killed, that the attack had specifically been an attempt on her life and that she had been seen by the killers through Olin's Focus, she was determined to track Olin down. Furthermore, Aloy's resemblance to Elisabet Sobeck had also been noted by Sylens, via his beck door into the Eclipse's Focus network. He had also heard HADES' kill order against her. By now fully realizing the threat posed by HADES and the Eclipse, though he was as yet unsure of its precise nature, Sylens resolved to assist Aloy on her quest, realizing that she was the key to stopping whatever it was that HADES was planning. The quest eventually led to Aloy twice encountering HADES personally.

The first encounter revealed to HADES that the Eclipse' attack on the Proving failed to kill her. The AI was extremely angered to learn that she had survived, and on its order, the Eclipse again made a concerted effort to kill her when she infiltrated the Eclipse base and crashed their Focus network. This attempt also failed. Having successfully crashed the network, Aloy went on to do what GAIA had created her to do: retrieve the master override in order to purge HADES.

Defeat
After Aloy's successful crashing of the Eclipse Focus network, HADES determined that the Eclipse were ready, and ordered them to launch their assault on Meridian, commencing its plan to capture the Spire. HADES' core was brought along, dragged by a Deathbringer. The assault was successful; the core was dragged through the city's breached walls and positioned at the base of the Spire. HADES interfaced with the Spire and began transmitting the signal to reactivate the Faro Plague. In various lands, Deathbringers, long buried, dug their way to the surface. However, in the course of her quest, and with assistance from Sylens, Aloy had become fully aware of HADES' goal of exterminating all life, and rallied a united force consisting of the Carja, Nora and Oseram to oppose the Eclipse. Knowing what HADES intended to do, and knowing the consequences if it succeeded, Aloy pursued and confronted HADES in the courtyard the Carja had built at the base of the Spire, wielding the master override bound to a specially designed lance that Sylens has given her. HADES attempted to stop her using an especially heavily-armed Deathbringer, but Aloy prevailed against it. Upon destroying it, she approached the helpless AI's core and stabbed it with the lance, activated the master override, and purged HADES. The activation of the override also broadcast the very same deactivation codes that GAIA had brute-forced and used to shut down the Faro Plague, shutting the reactivated Deathbringers down again. HADES was defeated.

Capture
But it was not destroyed. Following its defeat, HADES broke free from its now useless core and streaked off into the sky, having survived the purge. Far away, in a harsh, desolate environment, Sylens watched it. Mid-flight, it altered its trajectory and flew straight into a lantern-shaped device that he held. In a satisfied tone, Sylens asked his new prisoner if it remembered him, and mused that there was a great deal of information he intended to get from it, such as who sent the signal that unshackled it in the first place. Intending to get the answers from the imprisoned AI, Sylens walked toward the wreckage of another FAS-BOR7 Horus, eager to begin the interrogation.

Current Status
HADES remains Sylens' prisoner. Since Sylens gave his lance to Aloy to use as a means of wielding the master override, it may be presumed that he knew that the override would not destroy HADES, but merely purge it, stopping it from carrying out its plan to reawaken the Faro Plague. It is currently unknown what Sylens' intentions are regarding the information he means to get from the captured AI.

Abilities

 * Awakening Machines: HADES has the ability to reactivate the long-buried Corruptor and Deathbringer units of the Faro Plague. Presumably, GAIA would have had the Plague’s activation codes as part of its ultimately successful efforts to brute-force its deactivating codes. Thus, as part of Zero Dawn, HADES would have had access to them as well. However, it was unable to restore their biomass conversion systems on its own. It appears to be unable to restore Metal Devils, as it made no attempts to reactivate the Titan it had hosted itself in for almost two decades.
 * High-Level Intelligence: HADES possesses near-human cognitive functioning and an advanced understanding of mathematics and science. When scanned by the Focus, it is said that HADES' machine intelligence exceeds Turing 1.0, indicating its intelligence is indistinguishable from a human.
 * Non-Corporeality: While HADES generally remains within some host body, it is shown that it is capable of existing outside of a physical host.
 * Vocal Communication: Through Sylens's repairs, HADES is capable of speaking, albeit in a rough, unnatural tone.