having a setting idea of a big underground cave with false stars at the very top, and an elaborate ecosystem of fungi, little beasts, big worms and other bugs living in it. Some gnomes live there or in surronding, smaller caves with cities and shit.

Nobody has reached the top of the cave where the false stars are because if you climb too hide an horde of demonic bats comes from the side and kills you or destroys anything approaching it.

I want to write a story about it. A human ambassador to the gnome city makes a machine that goes up all the way (some gyrocopter, maybe?).

At the very top he finds some vampire twink or something who just watches the gnomes and they fall in love. I need to workshop the idea more