The Arkose Shelf
Beneath Crystal Suns
Far below the surface, there is a civilization that doesn't believe in us. In their world homo-sapiens are a minority who live along side two other hominid species: the Sevaku and the Fae.
Many, struggling to survive, attain credit to keep their family fed. The debt often leads to legally endorsed slavery. Indentured servitude has become normalized, while the culture slowly accepts new laws or punishments which effectively dehumanizes the servants. Many of the wealthy debtors utilize their affluence to seize spouses and children as assets, often sold to pay the mounting debt.
Their whole world is lit up by refracted light coming from the layer of crystal caverns above them. They use light as an energy source, which is primarily collected from areas that regularly recieve a beam of refracted light became laser focused for a measurable time; and on a regular cycle. There are a lot of these lasers being created, to one degree or another (ost being no stronger than sunlight) but they move on an irregular cycle due to the lasers themselves heating up a geological climate and eventually causing new caverns. It also creates earthquakes, cave ins, water supplies changing course, and other violent reactions from the planet- which is responding to the percieved attacks, in the form of its body overheating.
Beneath one of those crystal caverns is a water body -large enough to hold twice the ocean waters of the surface world. The water created canyons, mountains, and other features within the planet. These "shelves" have allowed life to evolve and thrive in ways few could have predicted.