Well, because I have such a broad area to work with, every single afterlife exists. Unless there’s intervention, you go to whatever you think will happen. The really important thing is that all the afterlives there are except for the ones from the God Worlds have multiple versions of themselves with multiple versions of the inhabitants. Because megaverse.
Egyptian
The main one I work with would be the ancient Egyptian Underworld because that’s where my MC ended up. As for what it’s like, well, that depends on your perspective. Outsides would find it weird but if you spend a lot of time there, it’s normal But, yeah, it’s the Duat so it’s got the 12 Hours and everything in them (e.g., River of Night, The Gates, Hall of Judgement, A’aru). A’aru (basically paradise) is quite nice (sunshine, beautiful nights, a big field, lots of happy people, etc) but my MC found it boring af
Most of the Duat is a giant night time desert but it varies hour to hour. I’m yet to cover all 12 hours but hours 4 and 7 make an appearance in some of my short stories. But it’s got stuff like sand, water, pits of fire, giant caves, underground realms, lots of snakes, a giant mountain, a lake made from fire, docks, other areas for certain Gods to dwell in. All that stuff.
Norse
In my most recent story there was a side adventure to Hel (the Norse one). Not all fire and brimstones as one would expect because it wasn’t actually described that way until the current major religions came into play. Hel is basically the same as this world only without things like love and happiness.
Greco-Roman
Also got the Greco-Roman one which makes an appearance, but only in the Mansion of Night (Nyx’s dwelling in Tartarus) has been shown so far. Basically, giant mansion made of night and filled with nightmares. Enter at your own risk. Also do NOT make Nyx mad. Oh, and there’s also a part of Cronus’ consciousness chained up in there.
The God Worlds
As for the God Worlds (the place where most of my books are set) there’s Desyen (Beyond), Void (the Void), Renyai (Peace/Rest) and KenKai (Punishment).
Desyen is, well, what’s outside Creation. It’s just Beyond. No one can reach it. No one knows if anything even exists out there. It’s existence only got confirmed recently after an, um, incident. But, yeah, my characters can’t reach Beyond. It’s totally out of bounds and should be out of bounds for everyone but, again, incident. No one knows what’s out there.
Void is pretty obvious. It’s the Void. It’s where there’s nothing, the space between universes/multiverses/dimensions. It’s part of the God Worlds’ mythology but everyone there knows that it is a real place. Void Beasts, the inhabitants of the Void, often come into Creation and do a bit of damage. But, again, Void is one of those places you can’t get to unless you have some VERY bad luck. Until recently, but that’s spoilers for my current and especially my next book (happy to explain if you’re cool with spoilers)
Renyai is basically the heavenly realm. Still under development.
KenKai is basically the hellish realm. Also still under development.
There’s also all the other Earth afterlives, plus all the ones for the aliens races, plus the higher beings, plus realms that have special requirements to enter. So, yeah, everything exists several times over except for the realms related to the God Worlds, the Void and Beyond because they’re all one of a kind.
Sorry if it’s a little confusing