This was my original idea for Alucar; What if at the start of the 20th century, a city was built to be a technological marvel. People flock to this city and are amazed by the wonders contained their in. There is a monorail and clockwork "guards" at city hall. The main creator of these things has his laboratory, known as the Steam Works, at the heart of this place.
Then tragedy strikes, as a massive sinkhole opens and swallows
everything. Not everyone survives, but those who do learn to adapt to
their new surroundings. It takes a year for city to pull itself
together, and now it is up to the players how to proceed. Stay in town
and deal with local issues, or strike out and explore the various
caverns branching off from Alucar? Go crazy and do both, maybe figure
out what caused the catastrophe in the first place?
Now I am thinking what if it is discovered by some spelunkers in the seventies and how that would play out? It would be creepier, that's for sure. Maybe do both, as a setting you could play a session where the city is discovered and then shift back to after Alucar fell into the earth. Just something to think about.
That is all I have for now, looking forward to coming up worth more stuff for you all.