It's really quite cool, I don't think I've ever heard of anyone doing a world like it. See, the rest of the unformed universe is a blazing white magical fire. The sphere in which the world resides - I'm calling it the Firmament - has a hole in it, and that's the sun. There's an inner layer of the Firmament that rotates the wrong way, and that's why the light of the sun diffuses blue over the daytime sky. Where inner hole is, that's the moon. It doesn't perfectly parallel our own astronomy - obviously, when the sun and moon align together, they open up a direct blasting portal of doom, rather than go dark in an eclipse - but it's close enough that the characters can walk around, look up, and see something they can think of as a sun.
I've also got a political map... just a bunch of random countries, basically.