It seems kind of strange that the Nora worship what is essentially a Cargo Cult, with the All-Mother basically being a door inside of a cave. Later on when Aloy actually goes into the door, it's discovered that one of the first generations of humans born (well, created) after the Faro Plague were raised inside by holograms that they called "mother" and "father." So the Nora are essentially right in saying that yes, the door that they worship really IS the All-Mother of humanity.
The idea of the door in the mountain being the All-Mother of humanity also plays into the Carja foundation story, with the Carja being "forced from the East" pointing to the beginnings of the Nora technophobia (what the founder of Meridian found in some ruins is essentially an astronomy textbook, if the worship of the sun and place names e.g. Prime Meridian is any indication) and the migration of what would become the Carja to the west. It would also explain, in part, why the Carja consider the Nora to be "savages."
The title that the Nora give their tested warriors: Braves. The last thing the robotic caretakers told their ill-educated charges before releasing them from the bunker? To be brave.
The Nora also emphasize being remembered - that the dead will live on in All-Mother's memory comes up now and then. When someone has a birthday, they're expected to spend that day with their mother, celebrating her, or if she's died, near her grave, remembering her. This goes back to those same caretakers - asked what it will do without the grown children, their 'mother' persona says "I will stay here, and sleep, and remember all of you."
The Nora policy of casting out those who break the rules, with everyone shunning the outcast but them being forgiven and returned to the fold, and letting them stay close, is very different from outlawing or exile that was common in human history. This is because it's not a classical outlawing or exiling, but rather a logical extension of time-out punishments the children faced while growing up, especially with the aspect of welcoming the outcasts back into the tribe once their time is up, yet still keeping them close enough that they can help or be helped if needed. This is exactly how time-outs work with children, with the adults sending the offending child away from the group and everyone ignoring them, but still keeping them in sight so they can keep an eye on the offender to keep them safe and out of trouble.
After seeing the holograms of the toddlers in the bunker screaming about seeing the sun rather than artificial lights, it becomes startlingly obvious why one of the factions worships the sun. Never even minding how they found the sunniest place they could to stay near it, clearly living underground your whole life leaves you with some issues.
Machine pathing:
It's weird for every single one of the Machines to have a traceable walking path (especially when the game partly rely on stealth element), but then again, with the in-built routine and all, why wouldn't they?
Also, unlike biological creatures who may improvise a path along the way with any rules being applied ad hoc, pathfinding algorithms find paths first from start to end and use heuristics (rules) to reduce computational time.
Also, the Focus acquiring their path would be blindingly simple. The machines aren't really built to defend against electronic attacks, and Aloy's Focus is a piece of technology from their time. All it is likely doing is just querying the machine for its current path and the machine replies automatically.
The Unintentional Uncanny Valley faces and expressions actually make sense after you find out that all fully biological humans are pod-bred, and had to be tutored by holograms who aren't the most diverse in terms of facial expressions from a really young age, which passed on through the generations to come. So it makes sense that the facial animations are off, that's what they learned from their robotic teachers after all.
Why are all corrupted machines vulnerable to fire? The corruption virus overclocks their systems to the limit making them that much more likely to sustain thermal damage when additional heat is introduced to the system.
They also use HADES nanotech, and one of the great hurdles of nanotechnology is that those tiny machines are very vulnerable to high-energy exposure, such as intense sunlight or heat.
Same goes for Corruptors and Deathbringers and why both are vulnerable to fire. Their control systems ("brains" if you will) possibly run on the eternity chips, therefore they can be powered up, reprogrammed and used by HADES. But they did spend the last 900 years or so buried in dirt, something that most likely corroded and damaged their mechanical and/or weather-sensitive parts, such as their cooling systems, making them prone to overheating, especially if they have to handle additional heat sources (like an arrow on fire sticking out of their radiators).
The Banuk choose to live where there are no ruins because they believe it proves they're hardier than the Old Ones. The Frozen Wilds DLC sheds light on this. The Banuk live in Wyoming, specifically near Yellowstone. But due to Ted Faro destroying APOLLO, they don't know about Yellowstone, so they've adapted what they can see to fit their own beliefs.
Why is the Yellowstone volcano's eruption is still going strong after all those centuries? Simple: CYAN is using it as release valve of sorts. That's a BIG part of why the caldera hasn't gone off yet.
Why can everybody a thousand years in the future still speak and understand English as it was broadly spoken in the midwestern US? Because the very first post-Zero Dawn humans were brought up knowing it and speaking it, and they passed on that language to their children. As the case of Iceland shows, geographical isolation can often slow language change to an almost unnoticeable pace if the pace of social change is also very slow (which is pretty much the case given the Iron-Age level the new humans were forced back to).
Aloy's reluctance to enter into a romantic relationship may not be due to asexuality — it may be due to her upbringing. She's been an outcast for most of her life, and never had any positive human contact besides Rost and a few people who will dare to speak to her when unobserved. Not only would this make her apprehensive about such a close relationship, but she'd barely even understand romance as we know it, aside from anything Rost could tell her about his late wife.
At first, the machines' ability to replicate themselves using light doesn't make any sense... unless you know a thing or two about 3-D printing.
Sylens' Lance, Aloy's spear upgrade, comes very late in the game where it could only really be useful in the final mission. This is because Sylens wanted Aloy to have it and use it against HADES. The spear must've been modified by him so that when Aloy stabs it into HADES, it will send the AI directly to Sylens, where he awaits to use his device to intercept it, as shown in the post credits ending.
Why are there so many useful plants, especially healing ones, around for Aloy to easily identify and harvest? Because GAIA deliberately seeded the Earth with them to make human life as easy as she could manage, especially after the destruction of APOLLO took all medical knowledge with it. Also, while the Zero Dawn Alpha behind ELEUTHIA (the subfunction responsible for the reintroduction of humans to this new world) gave strict instructions against genetic modification of humans, we are not told that the same rules were applied to DEMETER (the subfunction intended to regreen the Earth with plant life), potentially opening the door to GAIA engineering plants capable of helping humans rapidly heal from wounds which in our world would require weeks or more of convalescence.
Machine voices:
Why does HADES sound so unnecessarily terrifying? Because it was programmed by Travis Tate.
On the other hand, The Frozen Wilds shows Hephaestus has a similar voice. It's possible that, given the Zero Dawn group probably intended their descendants to interact with the subordinate AIs primarily through GAIA, the subordinates simply weren't given a prettied up user interface like GAIA was.
This last point makes quite a bit of sense if you consider how user-friendly CYAN is, considering she's meant to interact with humans on a regular basis.
Sylens also mentions that HADES didn't even have a voice when they first met. His current demonic voice might just be the only thing Sylens was able to rig up for HADES, but it's more likely that it was deliberately designed this way to reinforce the pseudo-satanic "Buried Shadow" persona HADES adopted to interact with the Shadow Carja.
Ted Faro doesn't have complete understanding of the big projects he's worked on, or of human nature. He didn't grasp that a loyal employee could implement the nigh-unhackable encryption he demanded and that doing so would mean it really was unhackable on any reasonable timescale. Project APOLLO was stored in fossil form so it could last, and the project headquarters was far from him. He deleted what was already loaded and would make it easy to access this information, but it's still there, waiting to be read and sequenced.
It should come as no surprise to anyone familiar with Greek mythology that GAIA's subfunctions went rogue, even though the means of which have yet to be discovered. After all, her namesake was overthrown with the rest of the Titans by the Olympians, several of whom her subfunctions are also named after (or their Roman counterparts).
Why do lancehorns, rockbreakers and some other machines built to dig in the dirt and have adaptations better used on machines then anything else? For terraforming and recycling, yes, but the other thing they can be used for is to find buried FARO robots and break them down and destroy the slumbering swarm no matter where they were so they can never be used again. GAIA really was trying her best to protect all life.
It may seem like a bad case of Failed a Spot Check concerning Aloy's "disguise" for re-entering Sunfall after her breakout on account of her big mop of red hair sticking out... but what does the Kestrel headdress look like? A big mass of red-dyed feathers. Since the Shadow Carja Armor is modeled after Kestrel armor, these combined with the Shadow Carja grunts probably not wanting to earn a Kestrel's ire keeps most of them from questioning it. Still a failed spot-check, but not nearly as bad.
Given the Derangement causing machines to be hostile to humans, it's not made clear initially how the Sun-King Jiran's kestrels managed to corral them into the Sun-Ring for sacrificial battles. Then, in the DLC, we discover how they did it: They used captured Banuk Shamans to make the machine-calls which would temporarily override them.
The triangle button (used to override machines) in this game is important for a reason. Aloy represents the Trinity in an interesting way - she is the "daughter" of Elisabet Sobeck, the "mother" of the current world, and the daughter of GAIA, who can be seen as the Holy Ghost in the machine spirit. Aloy is also a virgin birth without a father, albeit being a clone rather than having a supernatural origin.
Machine behavior:
While we know that the machines look like animals simply because GAIA found them aesthetically pleasing, it's not explicitly explained why they act like animals. However, the answer is simple: It's more efficient to program in specific behavior patterns that do what she wants than to individually control every single machine. Judging by the way that the machines produce and react to sounds, they don't even have any wireless capability; everything is done through natural responses. This is also how the Banuk can control them to a limited degree through horns made from machine parts.
This also explains much of the Derangement. HEPHAESTUS couldn't just flip a switch and turn every machine hostile (or even every machine of a single Cauldron, since he apparently had to hack them one by one). He was able to hack the Cauldrons to crank up the aggression for every machine produced, but couldn't do anything about the existing machines. This is why the tribes don't know exactly when the Derangement started; it took place slowly over time, as docile machines were destroyed and replaced with aggressive ones.
Gaia mentions she's coded so she couldn't interact with the humans until they completed the Apollo module and could take over terraforming. This explains why GAIA herself couldn't correct the cradles failing multiservitors who couldn't raise teenagers properly when APOLLO failed to open. Furthermore, it also explains why GAIA's message to Aloy focuses on seeing her as the same person as Elizabet. Aloy, being a clone of Elizabet Sobek (via project luminescence), doesn't count to GAIA as one of the new humans, so the communication block isn't in place.
When they first discovered Aloy, the High Matriarchs didn't technically hear her voice, just the echoes of it through the cavern. Appropriate for someone who is essentially an 'echo' of Sobeck.
One of Sylens' very few moments of genuine empathy occurs when Aloy is exploring the ELEUTHIA facility, and finds the locked door to the APOLLO learning center. The door is scribbled over with angry markings, indicating the children were angry about it. Sylens comments that naturally they hated it, it was a locked door. He knows exactly how those children felt: he himself spent most of his life trying in vain to get through locked doors, knowing that a vast wealth of information lay behind that he simply couldn't reach.
Of the Cauldrons the player encounters, Cauldron Xi is the only one that has failed, having succumbed to the elements and then been taken over for use as a base by humans. Well, of course it failed: it was built in Monument Valley in southern Utah. While that area was a desert before the Faro Plague, GAIA's terraforming evidently didn't get everything 100% right and rebuild Earth exactly as it was, because a thousand years later that desert is now a rainforest. The Cauldron's protections, built with desert conditions in mind, likely failed in the face of exposure to jungle conditions.
Why is there no swearing in the game, not even "soft" swear words? Because the first generation of the reborn human race never learned those words! ELEUTHIA educated them only to a kindergarten level, and there was no way that, in the absence of any knowledge beyond helper robots and preschool, they would ever even hear any dirty words. (APOLLO probably had them in its database, but Ted Faro had other ideas.)
This has changed in the sequel, as Aloy is now fond of using the word "shit" in various contexts. Even here, however, it's an exception that proves the rule, as Aloy likely learned it from studying the Old Ones' documents.
Elizabet choosing Travis Tate, a convicted criminal and Black Hat, as the Alpha of HADES seems peculiar at first glance. But upon closer inspection it makes perfect sense. One of the biggest challenges when developing HADES was how to get a it to successfully wrestle control of the terraforming system from a hyper intelligent A.I. such as GAIA. Travis was a highly experienced hacker known for sneaking into even the toughest security systems and stealing their data. This made him the best choice to coming up with a solution on how to enable HADES to sneakily take control of Zero Dawn from GAIA, without potentially damaging her systems in the process.
Fridge Horror
The components of Project Zero Dawn reference Classical figures. The game's Egyptian symbolism, however, is subtler and far more significant. The war machines' codenames, the fertility god Sobek, and Faro rhyming with 'pharaoh'. Ted Faro's private bunker is also described as pyramid-shaped, called "Thebes." Given what occurs to dead Egyptian kings, you are left to ponder what else he was trying to do near the end of his life... With the advanced state of the old world's technology, his narcissistic and selfish tendencies, and the lack of confirmation that he's dead, there's the chance that Ted Faro may actually still be alive.
And those fears were proven to be true in Forbidden West... Fortunately, his methods to extend his lifespan backfired horribly.
Machine isolation:
Consider GAIA for a moment, if you will. Built to keep vigil over the entire world once the last human life has ended, waiting for centuries as she slowly, tirelessly works to rebuild all organic life from the ground up, making the environment safe again, etc. For hundreds of years, alone. This is a sentient, intelligent AI being! She is capable of compassion, creativity, even self-sacrifice in the service of others. She feels grief for events that happened thousands of years before she was even created. And she is alone for centuries with nothing to do but build robots and work on rebuilding an entire eco-system. She watched helplessly as her mentor/creator/mother died, as Ted Faro murdered the Alphas who worked so hard to create her, and sabotaged APOLLO, putting her entire purpose for existing in jeopardy. "High-level directives" presumably circumventable by well-educated humans prevent her from communicating with the new humanity. And then one day, whilst things are seemingly going pretty well despite everything that's gone wrong, she suddenly receives a signal that really DOES put the entire project in danger, the only way to fix it being to resurrect her dead mentor/creator/mother, plan her own suicide and then hope for the best. And even that seemingly goes wrong when HADES corrupts the Alpha Registry and escapes. And considering she puts all of that into action mere nano-seconds after she receives said signal, those thousand years alone must've felt a lot longer. Her entire existence is really just one long line of succession of horrible things after another, interspersed with extreme amounts of loneliness. And then she dies, and almost nobody knows who she is, what she did for them, or that she even existed at all...
Made more explicit with CYAN in the DLC, who's less advanced and doesn't have enough intel on the situation to understand what's going on, but is more than advanced enough to fear rebooting alone and to be very lonely in the centuries that followed. She doesn't know any of the why and precious little of the what and is even more helpless to change the situation than GAIA. Small wonder she was eager to befriend Ourea and let HEPHEASTUS in.
Look closely at GAIA's subsystems - specifically, ARTEMIS, the fauna restoration module. It was able to re-introduce "pioneer organisms" into the new biosphere, but in order to restore anything weighing more than a hundred pounds such as wolves or boars, it needed human assistance. As in APOLLO-educated humans. This kept the programmers at Guerrilla Games from having to code for mountain lions or bears, but think about it; there is nothing in the biosphere bigger than a human. Because Ted Faro deleted APOLLO, humanity lives in world with no large animal life. A world without any of the beautiful animals we take for granted, despite the best efforts of the ARTEMIS team to keep the circle of life from breaking. No dolphins or whales in the sea, no lions or elephants or giraffes in the African veldts, no tigers or pandas in China.
Listen carefully to the Exact Words of GAIA's Dying Plea; "Three microseconds ago, the GAIA Prime facility received a data transmission of unknown origin. Its immediate effect was to transform my Subordinate Functions into unregulated, self-aware entities of a highly chaotic nature." Extrapolate on that, because GAIA references all of her subfunctions when she says "they are escaping";
The subfunction of first concern is of course HADES - which immediately goes on an omnicidal rampage.
HEPHAESTUS started building bots that attack humans - the tribes call this "The Derangement". Even worse, some of the models it's using are models meant for the other S Fs. Maybe they're not so chaotic after all... and Forbidden West showed it was all true. HEPHAESTUS is mad, and furious. And he's still out there.
AETHER is the subfunction dedicated to detoxifying the Earth's ravaged atmosphere. What means were used to do this? This means trouble for any tribes producing any form of air pollution. There could be places on Earth where lighting a fire brings a killer machine down on one's head. We're shown one of the means to detoxify the atmosphere: Stormbirds. You decide whether that makes the above less terrifying or even more.
ARTEMIS is the subfunction dedicated to the creation and reintroduction of animal life. And humans were supposed to help do this. Because of Ted Faro's sabotage, it never got that help. One can imagine some version of Casshan: Robot Hunter, an empire somewhere on Earth where ecoterrorist robots force humans to raise animals - and brutally punish those who fail in a task they barely understand.
DEMETER is the subfunction dedicated to the replanting of the Earth from cryo-preserved seed stocks. A combination of the above two; a zone where any animal that harms any plant is summarily converted into biofuel. And possibly poetry is involved.
ELEUTHIA is the subfunction dedicated to the cloning and raising of humans from genetic stock. This isn't as bad as most, but when it was first programmed, it was specifically restricted to preserving the human genome of humanity pre-Zero Dawn, not altering it. "A snapshot of human genetic diversity, literally frozen in time — the genetic quintessence of our species, unmodified." It isn't likely those restraints remained. Imagine a zone run according to Aldous Huxley's Brave New World, with humans bred to specific templates until they're pretty much unrecognizable as human.
MINERVA was the subfunction dedicated to shutting down Faro's robots. Now that MINERVA is self-aware, all it can see is all these other robots running around. The ones maintaining the terraforming. So this SF is most likely running around sabotaging the things keeping everything else going! You thought all those random dead machines in the wild were from hunters or other machines, but maybe not. After all, Watchers would be the first to go...
POSEIDON is the subfunction dedicated to detoxifying the Earth's poisoned seas and oceans. Imagine Greenpeace with a killer robot swarm. Hunting fishermen in canoes.
APOLLO:
The one ray of hope in all this crap? Despite Ted Faro's sabotage, APOLLO's icon is among those seen fleeing into the unknown.APOLLO still exists! There is still a chance for humanity's history to be recovered! Though it's probably really pissed that Ted Faro tried to delete it. There's most likely an area with 21st-century technology, with APOLLO lording over humans like a Dean Bitterman writ large.
However, things could also go another way. With access to all of human knowledge, and no GAIA to restrict it to educational functions, APOLLO might decide to act on its knowledge. What if it decides that, rather than knowledge being the cause of evil, humans are?
On the third hand, as custodian of knowledge, APOLLO should have context for its purpose, unlike the others. Meaning the best case scenario is that doesn't go monofocus at all and tries to act as a budget GAIA.
Unfortunately, APOLLO's case was Jossed. Faro destroyed all traces of it on Earth. Worse, he intended to take its place.
Itamen and his mother's lives prior to Aloy's rescue. Itamen is young enough that he would have either have been born during the Red Raids, or too young to remember a time before them, meaning that his mother was married to a sadistic monster for what was likely most of said marriage. It's made clear that she isn't the Sun King's first wife. She doesn't appear much older than Avad, Avad was VERY quick to offer her protection in addition to her son, and Helis's recording hints that she and her son are both horrified by the sacrifices. While she never gets any lines, it sounds like this woman's life has been absolute HELL for years while the poor kid has spent his entire life in fear.
How was an outside data signal able to so completely compromise Gaia's systems and take away her control of her subroutines? Odds are good that it used the same back door that Ted Faro insisted on being left in Gaia's systems. If so, that implies that even hundreds of years later Faro's actions are still creating fresh dangers to the world.
The ending demonstrates that all the genocidal Faro machines are still functional, just waiting for the right signal to awaken them to again ravage the world. And there are half a dozen rogue A.I.s formed from Gaia's subsystems out there in the world, any one of whom could seize control of them and put them to whatever purpose they wished, just by getting access to a spire.
GAIA says that her subsystems were corrupted by "a data transmission of unknown origin". Which begs the obvious question: where did the signal come from??? Sylens brings this up at the end of the game. If there's something out there that can corrupt every one of GAIA's subsystems with a single signal, it has to be at LEAST as technologically advanced as the Old Ones, if not more. And if even GAIA doesn't know where it came from, even the FARO robots may not be responsible. Which leavesa verydifferent option...
Ted Faro went and made himself a private bunker, just him and holographic porn stars, and killed the other people he was in contact with, leaving him in essentially solitary confinement. His bunker might be comfortable, but long term solitary confinement is defined as torture. Just like his other troubles, this is a hell of his own making, but this time it's not going to spread like wildfire.
First generation:
Thanks to Faro deleting APOLLO, the first generation of humans were only educated to kindergarten level. Imagine being released into a Wild Wilderness with the knowledge of a six-year-old.
One can only imagine what the very first humans where thinking when they discovered the consequences of "snuggling" for the very first time. Not to mention the very first exposure to the experience of childbirth after that.
GAIA, knowing that APOLLO was gone, would be completely aware that humans would emerge into the reborn world as kindergarteners. Even if she refused to re-introduce human-specific pathogens and parasites into that world, other species of filth would fill the empty niches. Vaccination would only last a single generation, as they would be unable to vaccinate their own children — and would only create specific immunities anyway. She would have to purposefully infect the first generation of humans — and fill the world — with myriad "nuisance" diseases just to jump-start the reborn human race's immune systems. No wonder most humans avoided the Cradle facilities once they left; their most vivid memories of their time within would be of the machines sticking them with sharp bits of metal and making them sick all the time.
GAIA wasn't exactly programmed with the Boy Scout manual. How many generations did it take for those kindergarteners to learn how to hunt for food? Knap flint? Build fires? Tan animal hide? How many generations of starving, defenseless, freezing, naked "blameless men and women" were there?
There are subtle hints — nothing concrete, mind you, just subtle hints — that whatever caused the FARO robots to go haywire a millennium ago is related to the signal that caused GAIA's subsystems to do the same. Just the idea that there's... something out there with enough ill-will toward humanity to destroy it TWICE is beyond terrifying. And it could still be around 1000 years later.
Let's have a look at the Focus devices, shall we? Sleek, innocuous and helpful as they are, the game shows or implies a few very disturbing facts about them.
They're easily hacked by anyone with basic understanding of technology.
A malfunctioning Focus can give off a painful electric shock. Keep in mind that the thing is worn barely a centimeter away from the user's brain at all times.
When Aloy tries to inspect the Focus she recovered from the Eclipse officer that oversaw the first Deathbringer's reactivation at Maker's End, HADES makes the damn thing explode violently. Now imagine what would've happened to the one wearing that Focus at the time. Combine this with the fact that pretty much everyone in the Old World wore a Focus, and remember that hacking them is obviously no big deal, and you have some A-grade terrorist material on your hands. Or a government/corporation enforcement mechanism. Or both. Probably the only thing that made it acceptable to the Old Ones was how readily privacy and personal sovereignty were already compromised in their day, which is horrifying in its own way.
Sylens at one point speculates that Focuses run on a miniaturized version of the Faro robots' biomatter conversion system. In other words, your glorified smartphone powers itself by eating your face. True, it's just speculation, but Sylens is repeatedly shown to be an extremely smart, extremely tech-savvy person who's never been wrong about anything in this department, so... yeah. It may be that it only consumed dead skin cells or similar stuff, but this doesn't help all that much.
But really, who doesn't want a little techno-buddy who shows you an AR interface while it helpfully slurps up your earwax?
Some of the stuff you find includes cybernetic eye implants, cybernetic heart implants, and pacemakers. Odd debris to find lying about, but... why? Why in random piles in ruins and not specifically in ruins of a medical facility? Because that is likely the spot some poor soul fell and was consumed by the Faro Swarm, and their implant devices were inedible to the biofuel processor nannites. Similarly, all the "ancient debris" you find other than the medical implants are essentially pocket contents, jewelry, and other personal accoutrements.
The Shield-Weaver outfit Aloy can get is a Game-Breaker, but it's based off of old-world tech that presumably quite a few infantry had. Infantry that had more armor besides the Shield-Weaving aspect, and used guns instead of Aloy's arrows. Yet still, they stood next to no chance against the utter dominance of the Faro Plague.
No two Tallnecks have the same layout of the ledges on their necks, which Aloy has to climb. One way to interpret this is that Hephaestus uses 'organic growth' algorithms to design machines, and since there are so few Tallnecks, it could not yet settle on a perfect design through generations of iterations.
, the fauna restoration module. It was able to re-introduce "pioneer organisms" into the new biosphere, but in order to restore anything weighing more than a hundred pounds such as wolves or boars, it needed human assistance. As in APOLLO-educated humans. This kept the programmers at Guerrilla Games from having to code for mountain lions or bears, but think about it; there is nothing in the biosphere bigger than a human. Because Ted Faro deleted APOLLO, humanity lives in world with no large animal life. A world without any of the beautiful animals we take for granted, despite the best efforts of the ARTEMIS team to keep the circle of life from breaking. No dolphins or whales in the sea, no lions or elephants or giraffes in the African veldts, no tigers or pandas in China.