Every Subordinate Function’s Purpose in Horizon Forbidden West

Every Subordinate Function’s Purpose in Horizon Forbidden West

Horizon Forbidden West continues the story of Aloy delving into the history and purpose of Project Zero Dawn, which operated with nine subordinate functions controlled by a master artificial intelligence. Horizon Zero Dawn’s story and ending dealt heavily with GAIA (Project Zero Dawn’s AI) and two of its subordinate functions, HADES and HEPHAESTUS. All three are key subjects in Forbidden West as well, but the sequel has a renewed focus on all nine subordinate functions. Without going too far into HFW spoiler territory, an overview of Project Zero Dawn and each subordinate function’s purpose follows below.


In the year 2064, nearly one thousand years before the events of Zero Dawn and Forbidden West, Dr. Elisabet Sobeck became aware of the Faro Plague, a rogue swarm of war machines that had become self-sufficient by consuming biomass to multiply. Sobeck predicted that the swarm would destroy all life on Earth within 15 months, and quickly began work on a way to restore life to Earth following the collapse of its biosphere. For those that didn’t play Horizon Zero Dawn before Forbidden West, the sequel takes some time to get players acquainted with Sobeck and her life’s work, even including a glossary of key figures from the first game.

Related: How Long Horizon Forbidden West Takes To Beat

Sobeck and nine of the Earth’s other leading scientists became Project Zero Dawn’s Alphas – those responsible for designing, programming, and implementing the project’s AI and subordinate functions, all of which are named after mythological Greek figures. GAIA, the AI that would control Zero Dawn, was developed and trained by Sobeck herself, while each of the other Alphas created the subordinate functions. Each subroutine was responsible for a different facet of Project Zero Dawn, which ultimately succeeded after nearly a millennia. HZD’s overarching conflict, inherited by Forbidden West, stems from an unknown signal that turned the subordinate functions rogue, evolving them into full-fledged AIs themselves.

GAIA’s Subordinate Function AETHER

GAIA's subordinate function designated AETHER is responsible for rebuilding Earth's atmosphere in Horizon Forbidden West and Zero Dawn

AETHER, named after a mythological personification of the bright upper sky, was responsible for reconstituting the Earth’s atmosphere. The glider Aloy uses in Horizon Forbidden West is only functional because of the fruits of AETHER’s labor. Little else is known about AETHER, and the name of its creator remains a mystery, though it was clearly at least partially successful in detoxifying the planet’s air.

GAIA’s Subordinate Function APOLLO

Created by the Alpha Samina Ebadji, and meant to re-educate humanity after the Faro Plague had been deactivated, APOLLO is one of Project Zero Dawn’s greatest failures. Ted Faro, who created the rogue swarm of war machines and bankrolled the project out of guilt, destroyed APOLLO in an effort to remove his involvement in the apocalypse from history. Driven to madness, Faro felt instilling the new generation of humanity with the species’ collective knowledge would lead them to the same end. The dire circumstances of Zero Dawn and the new and returning characters of Horizon Forbidden West are largely a result of APOLLO’s effectiveness being stunted. Project Zero Dawn would have attempted to return humanity to pre-apocalyptic knowledge levels, but APOLLO’s resulted in the creation of a tribal society with very limited knowledge of advanced subjects.

GAIA’s Subordinate Function ARTEMIS

GAIA's ARTEMIS subordinate function was responsible for preserving and recreating Earth's fauna in Horizon Zero Dawn and Forbidden West

ARTEMIS was created by Zero Dawn Alpha Charles Ronson to preserve and recreate Earth’s wildlife once the project’s terraforming infrastructure had made Earth a habitable planet again. Genetic material for a variety of fauna were preserved in the ARTEMIS facilities, which would be used to create clones once the biosphere could support them. ARTEMIS only partially succeeded in its directive, managing to reintroduce what the project called “pioneer organisms.”

Related: Horizon Forbidden West’s Side Quests Actually Respect Your Time

This subordinate function’s effectiveness was greatly crippled by the destruction of APOLLO. Once the new humans’ accelerated education was completed, they would have helped ARTEMIS recreate larger fauna. With no knowledge of ARTEMIS’ existence, the fledgling societies could not assist, and the subroutine was only able to carry out its creation of the pioneer organisms, such as micro-organisms, insects, foxes, boars, and other small animals.

GAIA’s Subordinate Function DEMETER

Horizon Forbidden West's DEMETER subroutine reintroduced Earth's flora after the Faro Plague

A Horizon Forbidden West trophy is planting real trees in imitation of the DEMETER subordinate function. DEMETER is essentially the flora version of ARTEMIS, responsible for reintroducing vegetation once the Faro Plague had been stopped. DEMETER was created by a mysterious figure known only as Naoto, who can be considered one of the more successful Alphas in Project Zero Dawn. The new biosphere in Forbidden West (and its predecessor) is incredibly lush, with plant life almost entirely consuming any traces of the extinct civilization from the 21st century.

GAIA’s Subordinate Function ELEUTHIA

Horizon Forbidden West's new story trailer primes players for the game's narrative

From an anthropocentric standpoint, ELEUTHIA was the most important subordinate function, responsible for birthing humans once the Earth’s biosphere could support them. ELEUTHIA would operate multiple Cradle facilities around the globe, using artificial wombs and robotic caretakers to rebuild humanity from cryogenically frozen embryos. Out of everything players need to know from Zero Dawn prior to playing Forbidden West, Aloy’s status as a clone of Elisabet Sobeck is perhaps the most important. ELEUTHIA succeeded in creating someone with the genes necessary to access the project’s buried facilities.

Although ELEUTHIA was largely successful in performing the functions programmed by Alpha Patrick Brochard-Klein, it too was affected by the destruction of APOLLO. The automatons in the Cradle facilities were only capable of educating humans up to a kindergarten level. When food supplies dwindled, ELEUTHIA was forced to release humanity into the wild, without the advanced knowledge from APOLLO that would ensure its survival. Aloy’s native tribe, the Nora, are direct descendants of the humans which emerged from ELEUTHIA-9, the door to which the Nora worship as the embodiment of All-Mother.

GAIA’s Subordinate Function HADES

HADES was a failsafe meant to restart GAIA's work incase a new biosphere was unsustainable

HADES is a primary antagonist in the series, and is a large part of how Horizon Forbidden West’s story connects to the original game. When the mystery signal turned GAIA’s subordinate functions into AIs, HADES went about fulfilling its directive to eliminate all life on Earth once again. 21st century criminal hacker Travis Tate created HADES as a failsafe protocol in the event of a newly created biosphere becoming unsustainable. If Project Zero Dawn wasn’t making satisfactory progress in restoring the Earth, HADES would essentially restart the process.

Related: Aloy’s Spear Is So Much Better In Horizon Forbidden West

HADES used the knowledge seeker Sylens as a means to build a following in the Shadow Carja cult known as the Eclipse. After GAIA self-destructed to prevent HADES from taking over its terraforming apparatus, HADES leveraged the Eclipse’s religious fanaticism in an attempt to gain control of the Carja capital of Meridian so that it could use the Spire to transmit reactivation codes for the Faro Plague, the countless machines of which lay dormant under the Earth’s new growth.

GAIA’s Subordinate Function HEPHAESTUS

GAIA's HEPHAESTUS subordinate function is responsible for creating all the machines players fight in Forbidden West and Zero Dawn

Alongside HADES, HEPHAESTUS has caused the most trouble for the new, tribal societies in Horizon. HEPHAESTUS was programmed by robotics engineer Margo Shĕn to be the terraforming arm of GAIA. The subroutine would construct and deploy legions of machines to detoxify the planet’s soil, water, and air. When HEPHAESTUS became an AI, it viewed the humans who hunted its machines as a threat, and began devising creations for the sole purpose of fighting back. This is a phenomena known as the Derangement to the tribal societies, and resulted in the animal-inspired machines of Horizon Forbidden West that players have to fight.

GAIA’s Subordinate Function MINERVA

MINERVA was the subordinate function tasked with brute forcing the Faro Plague's deactivation codes after all life on Earth was destroyed

MINERVA is the tip of GAIA’s spear, metaphorically speaking. Faro had created a sophisticated encryption for the rogue swarm, which could only be brute-force hacked over the course of several years. After humanity died out along with the rest of life on Earth, MINERVA would crack the encryption and deactivate the Faro Plague, broadcasting the codes from transmission towers like the Spire. Alongside DEMETER, MINERVA was perhaps the most successful subordinate function of Project Zero Dawn, successfully breaking the encryption so that a new biosphere could begin construction.

GAIA’s Subordinate Function POSEIDON

POSEIDON detoxified Earth's water in Horizon Forbidden West and Zero Dawn

Much like AETHER, little is known about POSEIDON and its Alpha. POSEIDON’s primary function was to purify Earth’s water, at which it was seemingly successful, at least in the regions that the games take place in. Horizon Forbidden West enemies that follow Aloy underwater are likely part of POSEIDON’s efforts, created by HEPHAESTUS to help remove toxins from the oceans and what would become drinking water when ARTEMIS and ELEUTHIA had completed their duties.

Next: Why Machine Strike In Horizon Forbidden West Is Better Than Gwent

Majora’s Mask Skull Kid 3D Model Will Bring You A Terrible Fate

About The Author

Kyle Gratton
(796 Articles Published)

A passion for video games was instilled at a young age when Kyle Gratton and his older brother were gifted a Nintendo 64 with Ocarina of Time and Mario Kart. Graduating from the University of Kansas as an English and History major, with a minor in Film, Kyle enjoys discussing literature, movies, television, and especially video games. He currently writes features and reviews for Screen Rant’s games section, and dabbles in short fiction occasionally. He can be found on Twitter @KyleGratton.

More From Kyle Gratton

Author: Deann Hawkins