Editing Machines (Horizon) (section)

== Background ==
The mid-21st century was dominated by the robotics corporation Faro Automated Solutions, which developed a series of advanced, autonomous military robots. In 2064, a glitch severed these robots from their chain of command. Equipped with the ability to rapidly self-replicate and consume [[biomass]] for fuel, the swarm became an unstoppable force that consumed all of the Earth's life in an apocalyptic event known as the "Faro Plague". To ensure life could eventually return, Dr. Elisabet Sobeck established Project Zero Dawn, creating an advanced artificial intelligence named GAIA to crack the swarm's deactivation codes and terraform the lifeless planet over centuries.

To restore the Earth's [[biosphere]], GAIA designed a new generation of machines based on extinct and extant wildlife. Manufactured in massive, automated underground factories known as Cauldrons by GAIA's subordinate function, HEPHAESTUS, these machines functioned as a mechanical ecosystem designated to purify water, detoxify soil, and reintroduce flora. By the 31st century, humanity had been reintroduced to the planet for generations. During this time, these terraforming machines were docile and generally fled from humans, allowing primitive tribes to coexist with them and hunt them for basic resources.

Approximately two decades before the events of ''Zero Dawn'', a mysterious extinction signal targeted GAIA, causing her subordinate functions to become independent, self-aware AIs. Without GAIA's governing control, HEPHAESTUS began to view the human tribes' continual hunting as a direct threat to the terraforming system. In response, HEPHAESTUS initiated "The Derangement", reprogramming existing machines to become highly aggressive and manufacturing entirely new "Combat Class" machines, such as the Sawtooth and Thunderjaw, to cull the human population. Simultaneously, the extinction signal awakened HADES, the subordinate function originally designed to wipe the slate clean if terraforming failed. In ''Zero Dawn'', HADES attempts to fulfil its protocol by manipulating a human cult into unearthing and reactivating dormant Faro Plague military machines, such as the Corruptor and the Deathbringer, to destroy the restored biosphere.

''Forbidden West'' introduces an additional faction of machines alongside the Faro and HEPHAESTUS creations. The Specters are highly advanced, futuristic combat drones created by Far Zenith, a group of wealthy humans who escaped the Faro Plague to establish a colony in the [[Sirius]] star system. Unlike Earth's machines, Specters are primarily composed of a solid inner structure covered in a malleable, white-gold armour made of advanced [[nanotechnology]]. The game's climax reveals that the Zeniths are fleeing from "Nemesis", a highly advanced, hostile AI created from the digitalised, amalgamated minds of the Far Zenith founders. Nemesis is revealed to be the source of the mysterious extinction signal that shattered GAIA; its goal was to destroy Earth's biosphere to deny the fleeing Zeniths a safe haven, inadvertently causing the Derangement in the process.