There are four of these -- it highly ties into the regional lore.
OG civilization -- a surface-based civilization. Very advanced, though they were barely aware of "subspaces" and definitely didn't know how to evolve them. This civilization had a couple big cities that cut into the two mountains where they were kinda drilling for resources or whatever. The civilization ended with the advent of the Dragonsun.
Cave Civilization -- the deeper parts of the cities were protected from the Dragonsun, so they expanded downwards. The surface kind of crumbled away and there was a lot of loss of life up there. This civilization did most of the legwork -- they really worked out how subspaces worked and could evolve them through specialized magic (which is now only found in Totems).
A hell of a lot of development, a lot of resources pulled in from subspaces. Lots of magic. Other than the impenetrable Dragonsun, everything was great.
There was kind of an inevitable mage war that happened here. Its victor became the antagonist.
Fallen cave Civilization -- more decentralized in various cave regions, helmed by powerful mages. They served the antagonist at first and things were kind of okay but they eventually rebelled or something so he cut their cities off from the world or something.
Present day -- very fallen towns locked away behind beacons, disconnected from each other, etc. Subspaces continued to evolve and animals became monsters.
Idk it needs some work. This is kind of an outline of an outline here.
The Surface is a barren wasteland. There are various geographic features but they all kind of reflect endless daytime and scorching heat -- ash, deserts, boiling lakes, that kind of thing. This is all due to the Dragonsun.
There are also tons of ruins throughout, many of which have melted into lava or crumbled away. A very post-apocalyptic feel. The civilization was pretty advanced and high-tech though so there are some crazy still-standing constructions up here.
The main mountain (where you start) city did survive and joined the rest of the civlization underground (connecting above VK) but during one of the civ collapses they sealed themselves off.
