dnd

hollow earth conspiracy theory but good

The Hollow World is roughly based on the hollow earth conspiracy theories, and takes place literally within the forgotten realms world. Its a relatively small country, inescapable, and unknown to the outside world. The only known point of access is a tunnel system within the planet, rivers run through it that seems to randomly open and close to the oceans and suck down things via whirlpool. These tunnels all tangle together and lead to one massive waterfall on a saltwater lagoon and river.

Rather than being arranged like the world in the traditional hollow earth theory, think the crystals inside a geode, the hollow world sits at the "base" of the inside of the planet and has its own warped plane of gravity, compare it to a terrarium in a hamster ball. For being so condensed, the environmental variety is great, snowy mountaintops and dense swamps exist in the same breadth as desert canyons and temperate forests.

The Hollow World has shorter days and nights than natural. A very small sun perches in the "ceiling" of the world by unknown means. It meanders across the sky and enters a cavity on one end of ceiling, apparently a tunnel connected to the rivers. In the morning it emerges from a similar cavity on the other side. Due to the nature of this sun, there being no round planet for it to refract around, or a moon that can reflect it, the hollow world has the darkest nights imaginable, the only light is man-made, and the occasional bio-luminescence. Thusly, creatures with dark vision thrive, others must keep sheltered throughout the night.

Various races and cultures have cropped up on their own, as well as a dinotopia-esque community of refugees who were taken in by the waterfall. The wildlife is almost entirely unique, consisting of animals thought to be extinct or entirely unheard of.

Same magic system as forgotten realms, some interaction between fantasy magic and real world alchemy/early sciences

gravity in the core of a world usually reflects the outside, pulling inward. The hollow world behaves completely separate, rather than be trapped on the inside edges- again like the crystals of a geode- it behaves as if the land is just in a large basin.

similar or lesser technology than basic landscape of forgotten realms.