If I may put down my two pennies on the planet issues I do have a few concepts for a pretty unique planet in a binary solar system that actually has a diagonal rotation.
Said planet was used in a weird hybrid-like world in which the planet had been colonized by humans with pretty advanced techniques and knowledge, but due to a series of natural cataclysms the knowledge of fabricating the tools and technology slowly faded and the items themselves either remained as relics that future generations could not use or just faded into oblivion.
So it was basicaly a medieval society with some pretty high-tech ancestry.
This is more so Sterk's first mentioned idea regarding anachronism and quite frankly it sounds like a good place to start fleshing out the universe.