We all have theories of the SK lore, and of course the obvious whats inside the core, the core I think that if you've been to the unknown passage, that's possibly one part of the core, but the background of it is pitch black with purple(or pink). But the core however, once you reach D29, arcade or after Vanaduke, you see a white glow, my theory is it might be the sanctuary which is the core, you might think different, as will I, so lets respect everyone's opinion. After defeating Vanaduke the story of SK somewhat felt short, and I know that the story line isn't finished yet. Here's mainly what I've been asking my self.
1: Whose King Tinkinzar? And what does he look like? Will he be much more of a pain to fight than Seerus(I think so...)?
Yes I know I did my homework :P but if you're curious to know and wondering "Whose that guy you mentioned" Click the link below
http://wiki.spiralknights.com/King_Tinkinzar
As it was said he might have had something with the creation the swarm(Which can be seen in unknown passage and SL boss levels which is only a swarm seed) and the Red Roarmulus Twins(Known as RRT, which is the shadow lair of the T2 boss Roarmulus Twins) explains something about the swarm, but doesn't show a lot of meaning, there's one theory there
(Once again, http://wiki.spiralknights.com/King_Tinkinzar )
Since the Ironclaw Munitions Factory(Known as IMF) is owned by the gremlins, we might as well consider UIMF(Ultimate Ironclaw Munitions Factory, the shadow lair version of it) a place where the swarm might've been created, in the beginning where the knights get the ancient generator and which razwog threatened to kill the knights with the generator(We'll make a fake one up, named Sirkull) so like I said razwog threatens to kill Sirkull and Rhendon(http://wiki.spiralknights.com/Rhendon) to reclaim the ancient generator preventing the knights to escape Cradle and he tricks the knights and decides to kill them anyway, but of course Razwog failed. After talk, talk and more talk, so the journey to the core continues
2: Whats inside the core?
Gremlins, main enemy in the game, who tried to rid of the knights off the planet, but for what? It has to be something the Gremlins are hiding, as they take orders from the core(http://wiki.spiralknights.com/Gremlins) The core however, for sure we know it's keeping the swarm inside, but if you look closely at the core on Depth 29, you can see the lock somewhat resembles a shadow lair key lock(Example UIMF, UFSC, etc) You can see the resemblance if you look closely at the key lock of a shadow lair and at the core, so possibly shadow lairs are an entrance to the core. As mentioned in the story Alpha Squad, which is a BIG part of the games story( http://wiki.spiralknights.com/Alpha_Squad) mentioned in the game saying they got inside the core, and the other knights, don't know how, No one knows for sure if Alpha Squad is captured, dead, or mind controlled by the swarm.
3: Different enemy families
I've been hinting this one for a VERY long time, if Cradle was built by Gremlins? How did the undead, slimes, or beast family even get on the planet? and if you put like say for example, a zombie and slime together, you can see they're not fighting each other, perhaps the swarm is mind controlling them to team up and get rid of the knights
Off topic: Of course battle sprites are coming out sometime soon, but whatever OOO is planning, they're probably planning something big to be put up in the missions
TL;DR
What's inside the core, Shadow lair key lock resembles core lock.
If you have a theory of your own, let the world know, our opinion may differ.
I stay on what fezor said: no matter how industrious gremlin can be, they can't build planets.
swarm: probably created by tinkinzar, but it got twisted, as the last echo stone says.
the core? ok, the alpha is in (most probably). but we do not know anithing else directly. I had a thread once, but I just have let it go.
for different families: we have different visions, so I'll stop here.