There are three main contributors to the Mythspace lore in terms of the game we play-- Troy, Zach, and myself (I prefer not to use any name-- Archivist will do fine). This is not to discredit the lore contributions that our players add, of course, but in terms of the information found here, if it's not from a sourcebook, it's from one of or some combination of the three of us.
Troy started Mythspace off with his continent, Jadeclyff, wherein the most stories have been told. Troy's works include Mariner's Tales (MT), Friend or Fae (FoF), Fiends in High Places (FiHP), and the ever incomplete Lowtide High (LT). She has taken a hiatus vis a vis DMing, but has still contributed the largest amount of information to the archive. Jadeclyff is one of many continents on the planet Praece, and her "sourcebooks" include The Adventurer's Guide to Jadeclyff, The Nomad's Guide to the Fey Forest, The Sailor's Guide to Zedar, and The Stargazer's Guide to the Planes.
Following the release of Jadeclyff, Zach added Kimarui to Mythspace. Kimarui is home to his original story, Spirit Garden, and has been in development since 2014. When adapting it to D&D, he made it possible for all folktypes as known in sourcebooks to be found on his world, and added five more folktypes unique to his Plane of Seasons.
Finally, inspired by my friends, I've stepped up with three original worlds of my own to add. My biggest world is Edynn, a world that is not a campaign setting, and has been in development as long as Kimarui. It is a hard sci-fi/fantasy world, meaning that it relies on real-world science to exist. It may not be a campaign setting, but the folktypes from Edynn are usable in campaign settings. There is only one portal to and from Edynn, and it exists on Kimarui, and spends the majority of campaign time closed. The next world I created was Foster, the ancestral home of all Mythspace elves; it comes with three new homebrew races. The most recent addition is Emvios, a planet with two continents shaped like stars and a sun that is made of crystal and shaped like a heart.