The "hostile" Gatekeepers:

[Klingenmeister]

Maybe I missed something, but do we have any actual proof of Gatekeepers attacking and killing Gate employees, beside the dubious Dr Cahn telling us? Could it be possible that the Gatekeepers are attacking us, because we are aiding a creature, that is claimed by Dr Manse to be a high level threat that needs to be contained at all costs.
A Creature, that told us to release another creature from the Gatekeepers, that also Dr Manse said to be contained at all costs, or it may phone home to anteverse 2.
Is Dr Cahn an infiltrator from whoever created the exor?

[Crochwhisle purple]

the bodies of gate staff are one of the proofs that they are. Also some dialogue and text that says that they are insane lunatics who kill anyone if they get in their way

[Monokuma]

The Gatekeepers are also probably hostile for recognizing you as the anomaly the player actually is. Even the sister of the unlost in front of the security sector door says "You are of our kith, but not our kin", which can be interpreted either as a kinship among gatekeepers, or a more literal definition that implies you aren't human.

Edit:
Also, Cahn is IS-0012

[Kairi ♡]

Since we encounter no GATE scientists at all in Gatekeeper-controlled area, it's safe to assume, that they are hostile to GATE personnel. Otherwise you would probably have alive scientists among them, that won't be hiding in some difficult to access places.

In a way, Gatekeepers remind me of Half-Life 2 Combine soldiers - they look like a human at first glace, but underneath their armor visibly deviate very far from human form.

Who changed Gatekeepers, remains unknown, but I suppose it's another force, which is antagonistic towards Exors. So we have, basically, lore of Half-Life Opposing Force here - alien race, that teleports to Earth to escape their pursuers, and pursuers, that also appear on Earth, both to stop aliens from escaping and to test Earth as it's next target.

So, Dr. Cahn is basically G-man.

Originally posted by Monokuma:

Even the sister of the unlost in front of the security sector door says "You are of our kith, but not our kin", which can be interpreted either as a kinship among gatekeepers, or a more literal definition that implies you aren't human.

I think it's more simple - just like Gatekeepers, we chase more power, but we aren't friends. Perhaps in the future we will have to decide, just how far we are willing to go in pursuit of power, which may influence ending.

[HalleysComet]

I don’t think so, because according to Hasta Tria, GK are not going to return dark lens, meaning they are going rogue, or maybe they didn’t really cooperate with GATE in the very beginning. Either case, they attacks employees to make them get out of the way.

[Kairi ♡]

Originally posted by HalleysComet:

I don’t think so, because according to Hasta Tria, GK are not going to return dark lens, meaning they are going rogue, or maybe they didn’t really cooperate with GATE in the very beginning. Either case, they attacks employees to make them get out of the way.

Not sure if we can trust words of former Order inquisitor.

[Kyna Tiona]

The first Gatekeepers you encounter will still attack if you don't open fire first, and the seemingly unhinged Gatekeeper Witch on the PA is levelling threats that seem addressed to GATE employees as much as anyone else. There's also a Jotun outside the Cloud Reactor that tells you in no uncertain terms that they're going to do to you what they're doing to the Order if you don't turn around, and he does this knowing full well that no GATE employee is surviving this without activating the Cloud Reactor. He's essentially saying "you can die quickly here and now, or you can find a hole to die in slowly". He's flanked by a pair of GADDs that have been hacked to attack GATE employees, so he clearly came prepared to make this ultimatum.

I suspect the lie in IS-0012's claim isn't that the Gatekeepers are trying to kill us all, I think the lie is that GATE ordered them to do it. He wants us to distrust our colleagues on the outside, because they're the only ones who could potentially come to our rescue. And probably also because there's a recording of Dr. Manse explicitly ordering all staff to stop IS-0012 by any means necessary. It'd be pretty bad for IS-0012 if the game actually let us follow that order, since you can't really shapeshift your way out of being deatomized.

[Kairi ♡]

Well, who else can give orders to Gatekeepers? Even if Gatekeepers are ordered to kill shapeshifter, in order to acheive that they will kill everyone.

[Kyna Tiona]

Originally posted by Kairi ♡:

Well, who else can give orders to Gatekeepers? Even if Gatekeepers are ordered to kill shapeshifter, in order to acheive that they will kill everyone.

I don't think they're operating on anyone's orders. The facility is overrun by an organization whose ethos is antithetical to theirs, and they know at least one of the scientists in said facility is a mole with enough information to have sabotaged the entire facility. By their reasoning, it's better to just wipe it all away rather than waste time and effort sorting things out individually. Plus, it's probably fun for them, and their moment-to-moment decisions seem to be primarily vibes-based.

[Kairi ♡]

Originally posted by Kyna Tiona:

Originally posted by Kairi ♡:

Well, who else can give orders to Gatekeepers? Even if Gatekeepers are ordered to kill shapeshifter, in order to acheive that they will kill everyone.

I don't think they're operating on anyone's orders. The facility is overrun by an organization whose ethos is antithetical to theirs, and they know at least one of the scientists in said facility is a mole with enough information to have sabotaged the entire facility. By their reasoning, it's better to just wipe it all away rather than waste time and effort sorting things out individually. Plus, it's probably fun for them, and their moment-to-moment decisions seem to be primarily vibes-based.

My guess is that whatever entity Gatekeepers encountered, it changed them, driven them insane, in exchange for power. So now we have 3 different factions - Exors, Order, Gatekeepers - and all 3 want us dead. And they also want each other dead.

[Darkchaos]

Originally posted by Kairi ♡:

Originally posted by Kyna Tiona:

I don't think they're operating on anyone's orders. The facility is overrun by an organization whose ethos is antithetical to theirs, and they know at least one of the scientists in said facility is a mole with enough information to have sabotaged the entire facility. By their reasoning, it's better to just wipe it all away rather than waste time and effort sorting things out individually. Plus, it's probably fun for them, and their moment-to-moment decisions seem to be primarily vibes-based.

My guess is that whatever entity Gatekeepers encountered, it changed them, driven them insane, in exchange for power. So now we have 3 different factions - Exors, Order, Gatekeepers - and all 3 want us dead. And they also want each other dead.

Regarding the Gatekeepers, Cascade has the Synaptic Labs which is what developed cybernetic and biological augmentations for the Gatekeepers. You can read about this in some item descriptions and emails. Recordings and emails also mention that they were very strange even before things kicked off. So the Gatekeepers we see are in their "normal" state and they were made like this by GATE.

IS-0012 (Fake Cahn) is correct that someone ordered a cleanup operation, although we do not know the exact reasons for it yet. When you visit Shadowgate and encounter the A2 creature, he also mentions that Gatekeepers have an addiction to mana which is something that not even GATE knows. It's quite interesting.

We will likely get our answers in the next major update. I'm pretty sure we will be visiting Keystone in that update, which is where all the GATE command staff is.

[Klingenmeister]

Originally posted by Darkchaos:

When you visit Shadowgate and encounter the A2 creature, he also mentions that Gatekeepers have an addiction to mana which is something that not even GATE knows. It's quite interesting.

I dont believe anything Cahn says. Hes not human and his actions line up with what Dr Manse warned about (Cahn trying to escape, Cahn trying to free the big creature in the portal). Cahn is going to give us the abiotic factor equivalent of the combine invasion, I promise you.

Does anyone remember his entire containment designation? I know it had "Camouflaged" and "Aggressive". Anything else? (I just googled it and it is: Designation: Sanc (Known and controlled)
AV (Attentive/Responsive)
AG (Aggressive)
CA (Camouflaged)

So nothing about teleporting powers and other stuff. Interesting...

[HalleysComet]

Originally posted by Klingenmeister:

Originally posted by Darkchaos:

When you visit Shadowgate and encounter the A2 creature, he also mentions that Gatekeepers have an addiction to mana which is something that not even GATE knows. It's quite interesting.

I dont believe anything Cahn says. Hes not human and his actions line up with what Dr Manse warned about (Cahn trying to escape, Cahn trying to free the big creature in the portal). Cahn is going to give us the abiotic factor equivalent of the combine invasion, I promise you.

Does anyone remember his entire containment designation? I know it had "Camouflaged" and "Aggressive". Anything else? (I just googled it and it is: Designation: Sanc (Known and controlled)
AV (Attentive/Responsive)
AG (Aggressive)
CA (Camouflaged)

So nothing about teleporting powers and other stuff. Interesting...

I believe 012 is a spy role creature send by big monster 117, this can explain why it can shapeshift and have charm in talk. That combines with Exor for violent invasion seems a perfect plan to me.

[Kairi ♡]

Originally posted by Darkchaos:

Originally posted by Kairi ♡:

My guess is that whatever entity Gatekeepers encountered, it changed them, driven them insane, in exchange for power. So now we have 3 different factions - Exors, Order, Gatekeepers - and all 3 want us dead. And they also want each other dead.

Regarding the Gatekeepers, Cascade has the Synaptic Labs which is what developed cybernetic and biological augmentations for the Gatekeepers. You can read about this in some item descriptions and emails. Recordings and emails also mention that they were very strange even before things kicked off. So the Gatekeepers we see are in their "normal" state and they were made like this by GATE.

IS-0012 (Fake Cahn) is correct that someone ordered a cleanup operation, although we do not know the exact reasons for it yet. When you visit Shadowgate and encounter the A2 creature, he also mentions that Gatekeepers have an addiction to mana which is something that not even GATE knows. It's quite interesting.

We will likely get our answers in the next major update. I'm pretty sure we will be visiting Keystone in that update, which is where all the GATE command staff is.

"Addiction to mana?" Emails mention, that some Gatekeepers have abilities, that are literally magic - like making words on the wall appear written in blood, without writing them. So perhaps they got "corrupted" by Shadowgate world.
I don't think Gatekeepers we encounter always were that weird, at least, until they discovered Shadowgate. As even description of fish from there suggests, that Shadowgate has some form of sinister energy - which, no doubt, can over time influence human, despite all protections.

As for reasons for cleanup operation - to preserve secrecy, I suppose. Even existence of GATE facilities, let alone stuff being done there, is all highly classified. We, as freshly hired scientist, already saw many things, that are far beyond our security clearance.

[Rae Nidae]

There's a couple GATE scientists in Reactor who seem anything but fond of the Gatekeepers. I figure if they truly felt safe around them then said scientists wouldn't be hiding from them as well as everything else

[Monokuma]

Originally posted by Klingenmeister:

Does anyone remember his entire containment designation? I know it had "Camouflaged" and "Aggressive". Anything else? (I just googled it and it is: Designation: Sanc (Known and controlled)
AV (Attentive/Responsive)
AG (Aggressive)
CA (Camouflaged)

So nothing about teleporting powers and other stuff. Interesting...

I don't think Cahn can teleport, I think his habit of just showing up places is more temporal. His containment is pretty low spec and they generally need you to open things for them so they can move on, and teleportation in abiotic factor thusfar has been associated with distinct sounds.