Strangers = snipes. We know someone else built haven, only critters around are strangers and snipes, most of the strangers are covered in snipes (even featuring a snipe perch), only other species of avians in the game (Owlites) were highly advanced before dem Kats wiped them out, and why would: a.) friendly gremlins continue to live as "strangers" when Punch and Vise live openly among the knights, and b.) hostile gremlin spies facilitate their own downfall by supplying knights with recipes for advanced armor/weaponry? Snipes, I tells ya!

Fu fu fu. They are really knights.

How are they that big? Because they haven't shrunk. The knights' origin is on Cradle, or Eldarc, as it was called. Almire was a mighty country, until Vanaduke went the core and was possessed by something there. (Presumably the Swarm) He quickly began collecting energy from the core. He was found out before he reached the amount he was trying gain. The tank he was using to store the energy was burst in a battle, and the explosion blew off more than half of Eldarc.

The knights that were still alive had a conflict that separated them in two groups: the Skylark Spiralians and the Cradle Knights. The first group thought Eldarc, or what was now called Cradle due to its shape and the way the core rested on the inside, created the Skylark the leave the remains of the planet. The latter thought the planet could still support life. They went their separate ways. Over time, they forgot about one another. Due to the training that they were having in the Skylark for invading a new home, they took on the name Spiral Knights. Also, due to malnourishment(they could produce food, but it didn't have much nutritional value and they couldn't make enough for everyone), the knights eventually shrank over the several thousand years wondering about space. They had forgotten completely about Cradle at this point.

Meanwhile, back on Cradle, the Cradlians eventually grew in numbers (not many stayed at Cradle when they split paths) and lived on the intact half. They became allies of the Owlites, and began to learn their ways. After a while, the core began building the planet up. This new side of the world was cold and mechanical, rather than built with soft dirt covered with a lush blanket of grass. This machine also began taking over the rest of Cradle. Mechanical monsters such as Lumbers and Trotodrones began raiding the Owlites and Cradlians. They were not prepared, as they were a peaceful group, and had forgotten the ways of war. A tribe of Cradleians known as the Kats also began harassing the Owlites, and turned themselves into living dead using the magic found in Owlite books. They began summoning their own dead bodies and the bodies of their enemies' dead as well. (The Cradleians, mourning for the Owlites death and extinction, found snipes, who reminded them of their dead allies, and began raising them as pets.) To make everything worse, the Gremlins were attracted to the power that the core had, and began invading the already crippled Cradlians. They brought with them more advanced robots and their experiment, Jelly cubes. (This started the same way the anniversary cake started: they threw in some dark matter because they couldn't get enough of their favorite treat.)

Even though many, many decades had passed, they still remembered the Skylark Spiralians. They began feverishly searching the stars for their lost kin. One day, they spotted a ship in space. At around the same moment, the Gremlins started hacking the Cradlians' (I will now refer to them as Strangers) computers, trying to uncover any secrets the Strangers may have had. What they found was images of a high power attack ship approaching. They nearly panicked, thinking that this was a ship packed with a powerful force that the Strangers had hiding until the Gremlins were off their guard thinking the Strangers were unable to defend themselves. The Gremlins began firing their Roarmulus Defender (the prototype of the Twins) at the ship. This brought it down in the crash that is found at the beginning of the game. That attack is what brought the Spiral Knights on Cradle. The Strangers took them in because the realized the power that the Knights held, but they didn't realized that the Knights were actually from their planet.

So, what do you think? This gives me an idea for a story. :P

Nah. Knights that discovered the extra short height modifier earlier than the rest o' us.