From publisher blurb:
Loosely connected fantasy demiplanes are all that's left of a fractured multiverse.
Everything was going more or less as it had for millions of millennia when suddenly the unthinkable happened. The multiverse, uh, kinda exploded. The fractured realities were sent hurtling (fifth-dimensionally) sometimes combining and reforming in a dizzying number of ways.
Once the dust settled, all that remained were demiplanes, strange fragments of reality the largest of which are only a few thousand square miles and the smallest of which is reported to be a five-foot dungeon tile, if you can believe it.
There's plenty to see and do on any one demiplane alone. And each would be completely isolated from the others if not for interplanar gates scattered among them. Those foolhardy enough to travel widely throughout the demiverse will find marvels and dangers in abundance, enough to rival your dreams and fuel your nightmares. One thing such intrepid people would never lack is adventure!
Demiverse Expanded builds upon the original plane-hopping fantasy campaign setting. This 39-page volume features the following:
7 demiplanes and 3 pocket planes., each by a different writer
18 pieces of original art by 8 artists
guidelines for creating your own demiplanes
history of the origin of the demiverse