Horizon Zero Dawn is set in a post-apocalyptic world around the year 3040, following the Faro Plague that wiped out all life and modern civilization. In the first game, Aloy wars against raging mechanical beasts and a corrupted AI bent on wiping out human life for the second time. As with any post-apocalyptic story, there is a lot of important lore that lead up to the apocalypse, and in the case of Horizon Zero Dawn, that timeline is crucial to understanding Aloy's world.
Aloy's first adventure began and ended within a year, but Horizon Forbidden West will send her to the West Coast of the former United States to investigate a new danger and save humanity from extinction once again. It's not entirely clear when Forbidden West will take place compared to Zero Dawn, but there are a couple of clues to speculate from.
Before the Faro Plague
Faro Automated Solutions was founded by Ted Faro in 2033, and eleven years later Elisabet Sobeck, the scientist who proposed and designed Project Zero Dawn, was hired as the head scientist. Elisabet was only 22 when she took the job, and while the first two years were relatively quiet, a crucial event happened in 2044: VAST SILVER.
VAST SILVER was designed to be a climate control AI, but it was a little too smart for its own good. It went rogue, and almost immediately the United States passed the Turing Act, which was intended to set limits on the sentience of machines. VAST SILVER isn't addressed in the main story of Horizon Zero Dawn and can be discovered only by scanning data points, but it's an important event to be aware of mainly because of the theory behind it.
The events of Horizon Zero Dawn were initiated by a mysterious signal that caused HADES, the apocalypse subfunction of GAIA, to go rogue. VAST SILVER was the first AI to go rogue in a major way, and it's unclear whether or not it was reigned in. Some fans believe that VAST SILVER may have been the signal that awoke HADES, or that it might be involved in Horizon Forbidden West in some other way. It's possible, given that VAST SILVER is a climate control agent and there is a clear emphasis on a gathering storm in the Forbidden West trailer.
The Faro Plague and Project Zero Dawn
On October 31, 2064, Ted Faro met with Elisabet Sobeck to discuss a glitch in a line of dangerous combat machines known as the Chariot Line. Despite being limited by the Turing Act, the machines had gone rogue and were no longer responding to commands. What made the situation apocalyptic was two key features Faro included in the machines: they were able to self-replicate at alarming rates and consumed biomass as fuel. Originally, biomass conversion was intended to be for emergencies only, but the glitch caused it to become the machines' primary source of energy.
A month later, Elisabet determined the machines were unstoppable and would wipe out all life on Earth within 15 months. Her solution was Project Zero Dawn, an initiative to design and implement an AI called GAIA that would work to override the Chariot machines long after humanity is gone, and could create new livable ecosystems once the machines were shut down.
To buy time, Elisabet suggested the controversial Operation Enduring Victory. This operation essentially sacrificed civilians to the bloodthirsty machines, keeping them busy while GAIA was being designed. By 2066, the Chariot machines had devoured everything.
The Events of Horizon Zero Dawn
The events that set the Horizon Zero Dawn story in motion began in 3020, when HADES attempted to take over GAIA's terraforming capabilities and bring about a second apocalypse. To stop him, GAIA sent instructions to ELEUTHIA CRADLE E9 to create a fetus using Elisabet Sobeck's DNA, and then self-destructed.
In GAIA's absence, the machines she created to maintain the ecosystems slowly started to become increasingly aggressive and dangerous. A year later, Aloy is born in Mother's Heart. Because of her mysterious birth, the Matriarchs send her to live as an outcast with Rost, who raises her as his daughter and trains her to run in the Nora tribe's coming-of-age ceremony, the Proving.
The main events of Horizon Zero Dawn begin and end in the year 3040, when Aloy is nineteen years old. She embarks on a journey to discover the truth about her origins and learns about Project Zero Dawn, GAIA, HADES, and how the Faro Plague caused the apocalypse. She defeats HADES before he is able to bring back the Faro Plague and humanity lives to see another sunrise.
Where Horizon Forbidden West Fits In
There are only a couple of clues that hint at when Horizon Forbidden West could take place. The first is Aloy's voiceover in the trailer. She says that the "Old Ones," meaning modern civilization, was extinguished a thousand years ago. Horizon Zero Dawn took place around 1000 years after the fall of civilization but Aloy isn't trying to be precise, so it doesn't reveal much. However, it does suggest that Horizon Forbidden West isn't taking place far in the future. Aloy also hasn't aged much in the trailer, further confirming that the games are close together.
The second clue is the Horizon Zero Dawn comics. Aloy disappears the day after defeating HADES, which might suggest that she was already headed towards the Forbidden West, but that's actually not the case. Talanah discovers her several weeks later and Aloy revealed that she was simply feeling restless.
The rest of the comics follow Talanah as she hunts down dark-armored machines, but with only five issues her journey isn't incredibly long. Because Talanah is practically confirmed to appear in Horizon Forbidden West, it will have to take place after her short story has concluded.
Finally, Sylens may help determined how far apart the two games are. At the end of the game, presumably on the same day as HADES' destruction, Sylens is seen capturing the AI and demanding to be introduced to its masters. In the Forbidden West trailer, Sylens is clearly up to no good and is likely to be putting whatever plan he has in motion. So again, Forbidden West isn't far away, but he also needs some time to get everything together before setting his plan in motion.
Taking everything into account, it feels like Horizon Forbidden West could take place six months to a year after the conclusion of Horizon Zero Dawn. That gives enough time for Talanah and Sylens to do what they need to, but not so long that Forbidden West feels like the jump from God of War 3 to the 2016 reboot.
Aloy is still doing her thing and the game will feel very familiar to the first, although Forbidden West is promised to be bigger and better. The reveal trailer hardly scratches the surface of what players will experience when the game releases.
Horizon Forbidden West will release for PS4 and PS5 in 2021.
