Little known cosmology models: omniverse

There has been many different cosmological models devised for D&D settings. The "omniverse" model simplifies the D&D cosmology to its bare minimum. It was first described in the 3rd edition Manual of the Planes and probably informed the development of the "world axis" model of 4th edition.

It is loosely similar to the cosmological models used by Glorantha and Exalted, which are themselves based on the eerily similar cosmological models of ancient cultures such as the Greeks, Egyptians, Mayans, and so forth. Variations of this model are also used by a number of retroclone campaign settings, such as the Auran Empire for Adventurer Conquer King System and the Dragon Empire for 13th Age.

Omniverse model (circa 5e)

The primary distinction between the omniverse and world axis models is that the former is based on a good/evil contrast while the later is based on a law/chaos contrast, though other variants may conflate this to good/law versus chaos/evil. While good and evil are fairly easy to understand (most of the time), the distinction between law and chaos generally varies by campaign setting. PCs will typically be on the side of law and fight the rampages of chaos; far less commonly the PCs will be on the side of chaos and fight the tyranny of order.

After a lot of consideration, I decided that the omniverse cosmology was the best fit for the world building of my campaign setting. It is easy for me to build around it because it does not have a lot of distinct parts unless you really zoom in. (I had particular trouble devising a model of the afterlife and undeath prior to adopting this model as a basis.) Since the basic setup is so simple, it is easy to add things onto it without disrupting everything else.