Working on my home setting, Calithi…
Every star in the known universe has existed since the “dawn” of time and is a locally/gradually omniscient/omnipotent sentient immortal. Their sphere of influence drops off at an exponential rate the further one gets from them. “N’tir” is the historically and scientifically accurate term for these beings, but many refer to them interchangeably as stars or gods, since both are accurate.
The names of all the N’tir is known, but they are not yet all discovered. The SEF’s (Shi’Kaen Expeditionary Force) long-term mission is to rediscover all N’tir so the core pantheon can communicate with them again. The topic of how the pantheon became split apart is a complicated and highly esoteric subject.
The Prime Material Planes
Any given plane can either be material, ethereal, or astral. The Prime Materials are the most well known and traveled by mortals, and to a material observer appear to be one contiguous and infinite space. This is however not so much an illusion, but rather just a symptom of the limited perceptions of most mortal sentient observers.
A prime material is formed by the envelope of power surrounding one of the N’tir. This envelope is theoretically infinite but given there are multiple N’tir, the envelopes don’t mix. If a plane/envelope is particularly large (because of distance from other N’tir), the edges can be unpredictable in their ability to contain material objects. Travel in these distant material zones is unwise.
The Astral Weave
All prime material planes and most non-prime materials are connected to the Astral Weave, a non-spatial plane. Since it lacks spatial properties, matter doesn’t ever occupy it; it’s purely a realm-state of information. Given its connection, it can be used for transportation (without transit). Any perceptions that travelers may have of the plane are purely in the minds of those individuals, pay them no mind.
The Ethereal Sea
All material planes have an ethereal counterpart which is coterminous. The given material plane is viewable from it’s adjacent shallow ethereal, but not vice-versa. Gravity and matter do not properly exist in an ethereal plane, though in the shallow ethereal other ethereal denizens can be seen and islands of reality exist where it might seem that one is actually on the material. The “deeper” (not a spatial relation) one goes into the ethereal, the more abstract things become, and the more material rules are lost. The deep ethereal is connected to all shallow ethereal planes and it contains veins and currents which lead to other material planes.
The Afterlife
Realms of the afterlife are not in fact different planes, but simply the landscapes that exist within the minds of the N’tir.
When they die, most mortal sentients return to become one with the god that created their species. This afterlife differs greatly from god to god. However, some of the N’tir have arrangements with one another to send mortal souls to one another for various reasons. In particular, Anubis seems to be in a position among the N’tir that allows him some measure of control where souls go. The politics of the gods is a subject of much discussion in the Empire.