Explore, discover, and document the dark, liminal reality known as the Backrooms, experiencing dread and isolation as you navigate it. We wish you luck in your travels.
I have thought about a retelling of the creepypasta about the "backrooms" (The SCP Fundation is more about one place to keep the menaces or hunting the monster of the week, without enough exploration).
It would start as a special place found in the "Haze", within Sigil. The first "levels" to be explored really are the floors of the ruins of "archology", a superskycrapper. It is by reinforced concrete but without remains of modern technology but empty spaces for cables or tubes, and latrine with siphon, without bad smell, but neither water. The look is a mixture of retrofuturism, gothic-noir and postapocalyptic punk. The are underground rooms, for parking of vehicles (nothing with a modern motor has been found) but also urban vegetable gardens using special artificial lights (source of energy power unknown). There are also ruins of buildings floating in the mist, but to go there you need flying movement or special bridges.
There are zones with "vertical forests", this means tall building with a lot of the vegetation on the walls. These are ruled by a strange lineage of driades who can use a special biopunk technology. They are willing to trade producer goods, and they sell graphene as replacement of felled wood. Also they are the suppliers of a magitek version of solar planers.
For inter-megapolis trade flying skyships are used, bigger as an aircraft carrier, but these can't be created, only found the remains in certain old battlefield (and later restaured). They work without fuel, energy or motor, and necromancer feels a familiar power. Even being necessary the vision of a ghost holey shell battleships flying on the cities isn't pleasing to watch.
Some zones are totally covered by clouds or mists, and some times brave explorers have found within floating mountaings with valious mineral recourses, but other times hostile savage tribes of humanoids.
* There are reports of false hydras.