Controversial lore.

I'm a bit confused,
I enjoy reading the story behind items, like the rose sets once belonged to a knight of rose and the sentenza which ones belonged to an evil who possessed angel eyes. All really enjoyable to read, but when I read it I find myself asking the question, who's history is this? Is it from Cradle? From Isora?
Are we all that's left from the entire Knight race? There's some nice comic (or manga, anime, etc. etc.) potential here btw, I'd definitely read it.

Yeah its kind of a mess. The origin of Trojans for instance - some instances they're described as warriors from another dimension, whereas the Arkus plot-line seems to suggest they're corrupted Sprial Wardens.

I actually agree with you that there is some pretty great potential for anime/some sort of ongoing show for all of this awesome story, though the disjointed stuff does present a problem sometimes.

I want to say it's history from other worlds, seeing how the Clockworks tries to create other worlds around it, creating its maze of depths. I'd only guess we know about these sort of things from either the strangers or old books from the Clockworks. The lore is pretty open ended other than what we're told directly.

we can divide lore in paragraphs if you wish, to make it clearer and more hole-y.
Knights: escaping from a civil war, searching power for unknown reasons. sent alpha squad, best of the best, to the core; they never returned. they wrote recon modules down while going down, and so we know they passed all the boss depths. you go search for em. (actually, by the time you go down, they are already dissapeared). you discover that entering in other people's houses/ dens/ working places armed make them attack you. insert arkus' story here. you beat bosses and reach the core. meanwhile you help desna various times (inserd danger missions here), assault the grand arsenal (insert OCH here), help impostoclaus on occasion (insert winterfest here), delve into the realm of the apocrea (inster shroud of the Apocrea here), and kill some black kats (insert katastrophe here).
fiends: they got stranded here somehow. they try to rise the legion of Ur. they lose control of Maulos, (if they ever had any) who seem to be appeared from nothingness.
gremlins: they work on the clockworks for unknown reasons. they also have a tyrant which has the crimson order under his control. crimson order members try to kill each other apparently. insert emberlight story here.
slimes: we don't know about jelly's origins. they have some kind of civilaization and they have royal slimes. lichens got here by crashing meteors, and that's pretty much it.
vanaduke: after his kingdom was conquered, he was cursed and drove mad by a mountain deiety, and now it's in the clockworks burning everything down.
kat tribe: got in war of the owlite, now dead, their leader is the "unluckiest kay ever". insert kat hoods lore here.
insert various gear lore here.
that's pretty much it. it's full of unexplained things that will never know. you know we won't know ever.

Things are more crazy than you think.
Take silkwings, for example. They're not entirely fiends, because they come from another dimension. However, they act like Tofu and absorb what they're around, including pain. How the devilites brought them here is for another day.

The description of the Sentenza is simply a reference to the Spaghetti Western "The Good, the Bad, and The Ugly," since "The Bad" was reffered to as Angel Eyes, and his character's name is "Sentenza" within the script.

Important note - Silkwings rarely spawn alongside fiends outside of arenas ;)

The trouble is distinguishing the Lore from the References. What is history, and what is merely a well-intentioned jape?

Oh I love these kind of things, don't be afraid to flood this thread with your thoughts about the lore we have been given so far.
As for arkus, both explanations might be true, seeing as his charge attack is somewhat tentacle-y, he might just be possessed by something from another dimension, Apocrea perhaps? The gem sticking out of his back might just be an incomplete, flawed obeslisk.
@thunder, gremlins work in the clockworks for known reasons, they work under the crimson order, who work under king tinkinzar, the mad genius who constructed the clockwork to imprison some kind of being, possibly the sanctuary, in it's core.
As for that matter, what is up with the swarm...? Any ideas?

This is my own theory behind cradle, taking what we already know from the echo stones and a lot of speculation.
King Tinkinzar, the gremlin king made a deal with a powerful being/sentient force. The being was seeking a way to shield itself from the darkness/the void.
Tinkinzar used the beings power to either dismantle entire planets, or copy/paste parts of other worlds that he constructed the clockworks with. From the Echo Stones we learn from the being that it is in a deep slumber, notice how every echo stone mentions dreams? The clockworks keeps the being in a deep slumber, while it constantly drains its power to keep the clockworks operational. The clockworks uses the beings power to constantly generate new worlds, and make the monsters that inhabit them.
From the Gloaming Wildwoods Echo Stone:
"Within my dream, I saw it open the void, felt its endless hunger."
"You are safe here, Knight. Within this dream, its many eyes cannot see you nor can its many arms reach you."
From the Ironclaw Munitions Factory Echo Stone:
"This world was created to protect me."
"Vulnerable in slumber, worlds were drawn to shield me from the darkness."
"This world has become my prison."
"In his madness, the architect betrayed the pact. Twisting his creation into a game of death, it now devours all who enter its iron embrace."
From the Firestorm Citadel Echo Stone:
"As I dreamed, it consumed."
"It devoured the knowledge of time... Memories of the dead... The hearts of kings and the souls of their people... Good and evil... It consumed."
"It grew stronger, endlessly mirroring itself within the space of my dream. Endlessly mirroring... Expanding... Infinite."
"What it was before, it is no more. Neither beast nor god, it is a creation unlike all."
"It is... The Swarm."
Now lets put these together. The being saw "It" open the void, and felt its endless hunger. This world has become my prison. In his madness, the architect betrayed the pact. Twisting his creation into a game of death, "It" now -> devours <- all who enter its iron embrace. As I dreamed, it consumed.
It devoured the knowledge of time... Memories of the dead... The hearts of kings and the souls of their people... Good and evil... It consumed.
What it was before, it is no more. Neither beast nor god, it is a creation unlike all. You are safe here, Knight. Within this dream, its many eyes cannot see you nor can its many arms reach you.
King Tinkinzar's creation is the clockworks, we know this already. King Tinkinzar is presumed to be either dead, missing or in a state where he can no longer operate the clockworks. Only the top ranking Crimson Order are allowed to speak with "him". If Tinkinzar is no longer managing the clockworks, who or WHAT is. I'm pretty sure Tinkinzar created an AI that would operate the clockworks even after his death, so the clockworks would continue to function. The AI opened the Void, which corrupted it. The clockworks are now being operated by this mad AI that has been analyzing every creature by dismantling them or "consuming it" and processing the animation. What it was before, it is no more. Neither beast nor god, it is a -> creation <- unlike all. So, this mad AI now controls the clockworks, and can use all of its functions however it wants. It created the shadow lair by rewriting the monsters DNA/Code and infusing them with void energies, corrupting them. The Void monsters we see in the unknown passage was created the same way, they are the AI's improved monsters. Its just continuing Tinkinzar's research in its own mad ways, consume new information, improve and create. "Within this dream, its many eyes cannot see you nor can its many arms reach you." The AI can see everything that happens within the clockworks and the worlds it has created, and its many arms are all the monsters it creates. However the sanctuary was created by the being inside the core to protect the knights for a short while, and prepare them for the battle ahead. The enemy is the very clockworks themselves, or at least whatever is controlling them.
The Crimson Order wishes to keep their kings greatest creation operational for as long as they can, this is their sworn duty. They probably already tried to stop the AI, which could hint at all the gremlin corpses found in the unknown passage. The Crimson Order is also probably split into multiple factions, since Warmaster Seerus created weapons to eliminate other Crimson Order gremlins that stood in his way.

Can't power the Skylark
Uses the same power to power thousands of Brandishes.
PSA: Everyone stop crafting Brandishes so we can power the Skylark!

I think you might be on to something with that AI story.
But tinkinzar is far from dead as far as I'm concernec. The being asked tinkinzar to construct the clockworks to protect him. just to draw in worlds as a prison. But tinkinzar betrayed him and that's when the monster came in, they weren't here to begin with.
Also concerning the void, it consumed the hearts kings and souls of it's people, pretty sure that's a reference to what happened to Almire and vana.
It should also be noted that while the void corrupted vana's heart, his soul might still be safe, in fact vana's soul might even be the being that's imprisoned inside the core, since he wasn't always evil. It would make sense, seeing as when the void consumed vana he sought help protection.

I guess this is general lore thread.
The armor our knights wear are power armors. Whenever we take damage, the suit is taking the damage and not us, which is why our characters don't die when we lose our health, upgrading and forging gives us more health, and why a spark of life actually looks like a spark. Plus, it explains why we can hold Troikas with one hand and a Volcanic Plate Shield in the other, the suit picks up most of the slack. And the Guardian knights at certain areas are just regular knights in really big armor things. Our face is actually a screen on a glass visor to make us big scary knights less frightening and more personified when doing civilian work missions.
And the Izola Civil war is over Minty Cola or Shaky Soda being the better brand. And our knights are part of Team Shaky.

The clockworks were originally made to protect the thing in the core, but Tinkinzar went mad. I think Tinkinzar is in a state where he can't lead the gremlins, so the Crimson Order does it while their king is MIA. We don't know where he is, he might even be dead.
Yeah, thats pretty much a reference to almire.
I highly doubt its vanaduke's soul thats inside the core, in fact Vanaduke was never evil, his soul is/was still trapped in the past, believing he was still defending the kingdom of Almire from enemies. While FSC/Almire was not created by gremlins/clockworks while UFSC is an artificial, improved version.

I don't think shadow lairs are really 'canon'.

Alpha Squad's Parma mentioned that they were attacked "by the shadows," so I assume it has to be the Swarm & canon, since it is mentioned in a Recon Module.

Oh, I think the Swarm is canon, I just don't think that the shadow lair part of shadow lairs are canon.

I believe that Shadow Lairs are a dream given to us by The Child, or an alternate dimension where the swarm has escaped the core and is infecting the clockworks.

That's a really interesting theory. Something like the Ihan Crystal from Starcraft 2, where we're looking into memories of the future?

The core? It's a prison! You're being conned, don't you see? It is actually dieing to devour you! It's in shackles right now, but that won't be long if I just step aside. The Clockworks are a way to drain the hideous monster of its energy, yet even with the giant Clockworks, it will still take a million years for it to die.
Don't unleash it! Don't bring its vial poison on you! Don't let it's frost tear you to pieces! Don't let its illusions bring you into a false wonderland! Do not try to harness what you cannot understand!
Heed my warning! ...Hmph, fools you are...En garde!
~Words from the Doomsday Watcher~

Here are my versions
About the Morai Wars, Knights, and the Strangers
The Isorians fleed from the Morai, creatures that made them almost extinct during a war. Why they fought is unclear. The crew of the Skylark, after fleeing, started looking for a power to rescue their home from the Morai. They found Cradle, and as they were about to land, something from inside the planet, from the Clockworks, shot them with pink lasers. (ITS THE SHWARM BECOOZ ITS PEENK) The knights safely evacuated (or a part of them, at least) the Skylark and found themselves in the regions of Haven and the Rescue Camp. The Isorians sealed a deal with the strangers to live in their mining outpost/town, Haven. There, they detected energy sygnals coming from the core of the planet. As not all systems were fully offline, they sent the Alpha Squad and ordered them to drop the Recon Modules once in a while. The Alpha Squad made it to the Core with their Recon, Parma, being semily infected by what seemed to have attacked them in the Core Terminal - living shadows, or as we know it now, the Swarm. The core opened for them just as the end seemed nigh, probably out of empathy. (The Core being must also have been capable of curing Parma, else it wouldn't let her in, right?)
About the Gremlins, Tinkinzar, the Core being and the Swarm
At some point, when Cradle was a normal planet, the Core Being felt vulnerable, or was. It's unclear why, but unknown entities I will reffer to as "The Ancients" decided to defend the Core being and went into space to find methods of doing so. What they found was the Gremlins, who were mechanical geniuses and explosive maniacs. They sealed a deal with them and took them to Cradle. The Ancients must have passed away or were killed by the Gremlins after the great gremlin king Tinkinzar became a maniac. At some point, the Gremlins started building the Clockworks so the Core Being could be defended in them. It was some sort of bunker. Tinkinzar at this point became a maniac, locking the Core Being away in the Core, and putting it in Slumber. Before that happened however, the Core Being left behind some Echo Stones, which as the name implies, echo it's voice. Not only locking away the being, he also turned the Clockworks into a huge mouse part that consumes whoever enters. The Swarm was probably made as a weapon against whoever wanted to get the Core Being, but it got out of control and Tinkinzar attempted to lock it away in what is now known as the "Unknown Passage". However, it got Tinkinzar and infected him, making him the madman he now is. (It's also possible something similar happened to Seerus, but I highly doubt it.) The Swarm got out and keeps infecting the Biospheres of Gloaming Wildwoods, Royal Jelly Palace, Ironclaw Munitions Factory, and the Firestorm Citadel as they are moved to the right wheels and depths by the gigantic cogs and cranes. These worlds must be right above the Unknown Passage when this happens. The only thing keeping it from spreading even farther are the Knights that clear them and destroy their sources... for now.
About the Apocrea, the Kat Tribe, Fiends and Almire
I honestly don't know what the Apocrea are. Huge spirits that live in the so-called dimension of the Obsidian Nexus, which somehow is stuck in the Clockworks. They feed on souls of the living, and I sense some connection between them and the fiends. That's all I know about them. As for the Kat Tribe, they had a war with the Owlites for unknown reasons, and the Kat Tribe hero Margrel has accidentally read an owlite tome known as "The book of Grey feathers" during the siege on the "Owlite High Academy of Magicks", dooming both races to death and cursing some of the Kats including himself. The Kats didn't rest tough, and returned to the material realm and became what we call "Spookats". Mewkats are little Spookats, that must have been doomed when they were little. Konjuring Kat wanted the kat tribe hero Margrel to be with them (he seemingly could rest), and used hexing rituals. Once he had been given the Book of Dark Rituals, stolen from the Black Kats who stole it from the Moorcroft Manor Archives, he summoned Margrel to the material realm. However, something did go wrong and the thing he summoned wasn't Margrel. It was unintelligent and wanted to kill the living.
The Fiends... They are stranded on Cradle much like us, Isorians/Spiralians/Knights. They came from another dimension known only as "The Underworld". The Trojan-family fiends however, they are the subject of many theories. Some say they are dead knights that refused to leave, others say they are creatures created by the Devilites. My personal guess is that the Trojans were actually other intelligent beings, cursed by the Devilites to become what they are. Arkus was just in an early stage, tough. It is unclear why the Warden Set heavily looks like a Trojan, tough... What is even more strange is that the icon of the Knights is a Trojan with open eyes that don't scare you.
Almire was a kingdom, maybe on Cradle, that was very proud, successful and pure. At one point Almire was attacked by someone or something, and the king, Vanaduke, and some of his troops fleed from Almire to an unknown mountainous location. Vanaduke has pried to Vog to give him power, and the deity granted the wish and turned him into some metal-armor being. However, Vanaduke couldn't tell friend from foe, and killed all of his troops and returned to Almire, defending it. Because he couldn't tell friend from foe, he killed all in the kingdom with his flames and Vog cursed the entire kingdom to never burn away. Countless souls couldn't rest and became fiery dust zombies known as Slag Walkers. The king's royal guards became known as Almirian Royal Guards, which probably was their title before the events.
*sigh* Phew. Any questions?

How did the Slimes get to Cradle? Was it by a meteorite?

How did the Slimes get to Cradle? Was it by a meteorite?
This seems likely. This is how I imagined them getting here anyway. Lichen at the very least... not sure about actual Jellies.

I think the Jellies are the real, original Cradlenians or whatever.

You had some very good points and have changed my view of SK.
However my personal theory about the FSC is that the Almirians were attacked by beasts, probably some early form form of Snarbolax + friends. Remember, the Siege of Almire was recorded on a very old text in the Owlite Keep and was notably very old.
My proof of this is the first and only words the Duke speaks to us knights:
What's this? More wolves hungry for the blood of Almire? Our great kingdom shall never fall to the likes of beasts!"
Beasts!!!!!
Furthermore, I believe that these "beasts" that attacked Almire is the legendary beasts Vog and his/her "cubs"
1st, with Vog Cub Coat, the fire resistance points to the fact that the cubs had some experience with FIRE. Perhaps the VOG cubs' (or the VOG's) FANGS were flaming...
2nd The Almirian Seals can buy the Fang of Vog. Looking at some of the other boss-related token rewards, the seals reflect things used/near the boss EX: Fruitious Fangs => Snaborlax related items. So, I conclude that the Fang of Vog was knocked out of Vog's mouth and was extracted from vanduke's corpse where the fangs were buried (when the Vog attacked him). Also, I'd like to note that the sword itself was probably crafted by Brinks (etc.) or possibly given to Vanduke to smite his enemies (Vog is described to give power to people)
3rd FIRE in FSC. Looking at the stats for the Almirian armour, it's fire weakness, the surrounding atmosphere of FSC, and it's supposed pre lush landscape described on the wiki, I would conclude that the Almirians did not want shadow fire everywhere in their kingdom... So where did the shadow fire come from? Yea.. Vog and it's cubs did that. I can just imagine them spewing magical fire everywhere....
All in all, I think that the living Vanduke asked Vog for help, got it, did something bad, and Vog + friends attacked Almire as a consequence.

@crashburnboom
Sorry, but you couldn't be more wrong. I liked your ideas though, however, Almire was attacked by 2 rival kingdoms who feared that Almire would grow far too powerfull for them. So they decided to join forces and devestate Almire before it would grow too strong.
In that war vana fled to the mountains for many years where he begged a dark being who cursed him to give him strength to reclaim his kingdom. It was then that the being transformed vana into the monstrousity we know today. The being also gave vana an army of (not sure if it's literal or just a name) fiends to destroy the oposing kings. When he returned to Almire he reduced everything and everyone to ashes.
In other words, vana was the one who destroyed his own kingdom while burning everythin in his path, still your idea that the being that granted vana his power and army is actually vog may be true.
EDIT: However, I am still fairly convinced that the being inside the core is vana's lost soul. Seeing as the vana boss gives you a broken crest of
almire, and the shadow lair vana grant you a true almirian set, which still could mean vana's soul resides in the core or at the very least, in the sanctuary. The swarm might've been the fiendish army that helped vana destroy almire.

@Scirio
That's fine. I didn't expect it to be true anyways :P. Knew something was bothering me...
However, Vana might have interacted with the Vog in some sort of manner (the Snaborlax might be related to the Vog but I am in no way sure) Maybe the Vog gave his some power/weapon? (that would still explain the FOV weapon)
It would be awesome tho if we could fight a Vog Cub (the Vog itself might my too OP if the legends are true)
Edit: Spelling
Sadly, the developers have chosen not to expend much energy on making a coherent story for the game. All we know is bits and pieces.