The Fell Gard Codices by Matthew Surridge

A group of wanderers find themselves in a legendary dungeon as big as the world, a place filled with wonder, magic, and treasure — but also monsters, traps, and danger. Some of them come to believe there is a reason for them to be there; others just want to escape.

The Fell Gard Codices is an attempt to find meaning in chance, pattern in chaos. The dungeon and everything in it is generated randomly, and the story emerges from this unpredictable matter.