Chain of Worlds
"What we should do at some point is just make a setting, take a party of adventurers, drop them in there and say 'Go Wild.' No metaplot."
The Chain of Worlds is a series of strange, experimental world built of 20 interlinked, triangular demiplanes. At the center, the elemental chaos powers reality. Orbiting the isocahedron are a pair of rifts, one to the Positive Energy Plane, one contained rift to the Negative Energy Plane. Good luck!