Two thousand years ago, the world was covered by a deadly fog. The only refuge were the floating sky cities. This is where you find yourself in Cloudsea, a new RPG setting guide for 5th edition D&D that's up on Kickstarter now.
From the campaign:
Welcome to Cloudsea, an approximately 60 page setting primer and supplement for your 5th Edition Roleplaying Game! This supplement is brought to you by Beyond the Horizon's Kim Frandsen, writer of such works as Keeping it Classy: The Barbarian, and myself, Miguel Colon, writer of Legendary Games' upcoming Boricubos setting as well as the writer of Cloudsea as a whole.
Two-thousand years after the world was covered in a mysterious fog now known as the Cloudsea, killing nearly everything on the planet with its radiation, society has recovered due to the ingenuity of those who saw the end coming: the gnomes, who built the massive sky-cities which people live on today, the humans, who were gifted with the foresight of tragedy in the first place, and the ratfolk, ingenious workers who know how to make the best out of any bad situation. After reaching the skies, they met the mysterious nimbus nymphs who lived in the clouds and due to magical and technological advancements, were able to build the android race in order to be subservient to the other four.
The campaign's up and over its funding goal with 28 days to go.