An Atlas of Lengsnacht

From the introduction:

The Book of Lengsnacht is a fantasy world set just after a time of enormous upheaval. The world is a century removed from Lengsnacht, an unexplained supernatural cataclysm that destroyed a massive portion of its civilized lands. Now, airships travel the hundreds of islands floating in the Sky Country above Lengsnacht’s site. Below is the Nacht Sea: a decrepit, corrupted ocean, forever changed and ruined by the event. The rest of the world has been forced to adjust to the Nacht Sea’s presence as they manage statecraft, clashes of kings, magic, westward colonization and advances in technology. A new era of change and adventure is unfolding, but all under threat of another apocalyptic disaster.