As an expansion to my past posts on the Kingdom of the Wheel, I extended the core idea into something I call the Wheel Kingdoms.
Essentially, this posits the idea of multiple iterations of the Kingdom of the Wheel, each one circumscribing a set kingdom with its own sovereign, its own set of cities along the circumference of influence, its own set of Saeculum (a term for both the rules of magic that are dominant within its purview and the metagame rules that govern gameplay). There are special cities known as Intercities where two (or more) Wheel Kingdoms intersect, and those cities are semi-independent and follow their own set of rules geared at sustaining diplomatic relations and trade between the Kingdoms in question.
All kingdoms are governed by the Overking and his Adamantine Court, who sponsor the efforts to rebuilt the entire network of Wheel Kingdoms against the end of all things.
The purpose of this: an attempt to create a glorious sandbox of interlinked kingdoms with their own Megadungeons and nearby threats and concerns, along with a rationale for sending players into vastly different cities and landscapes quickly and cheaply (the teleportation spires of the Wheel Kingdoms), and a rationale for different rules of magic and artifacts and cultures.