Instead of addressing actual problems, I’ve been working on a complicated Underdark setting for what amounts to a one-shot.
Siddím is a riff on Thomas Gold’s Deep Hot Biosphere idea: life originally evolved as bacteria and unicellular organisms deep underground: slimes, basically. (I haven’t read Gold’s book and just using it as window-dressing.) Siddím: a subterranean slime pit where life evolved from mindless ooze into a civilization of Slithering Trackers, who built their city here. In time, fungi evolved to feed directly off the caustic slimes, leading to Myconids. Throw in some Aboleths in a deep underground lake where some slime-streams meet. Sprinkle with Duergar, Troglodytes, and a “lost world” sinkhole populated by neanderthals and giant bats, and you’ve got the region, a sort of Icelandic Underdark. Siddím is a holy site to the Jubilex cult, which uses purify food and drink to feast on the slimes, and relies on a Slaver Guild to supply their landlords with fresh meat.
All of that is background scenery.
The one-shot I’m working on is a jailbreak by a group of slaves owned by a trading coster of Mind Flayers, who have emerged from an abscess in the Collective Unconscious to trade with the Aboleths. The Mind Flayers have set themselves up in a Fortress Dam constructed ages ago by the Duergar, but has since been converted into a pound lock by the Aboleths who use it to portage over a really steep and rocky subterranean rapids.
I don’t want to think about the number of hours I’ve spent working on this thing, but it’s involved doing Internet research on speleology and cave ecosystems, Leonardo da Vinci’s plans for mitre gates (PDF), coming up with bizarre Dungeon Theology, revisiting the 2e Psionics Handbook, and playing around with famous D&D monsters.
This is a crazy hobby.