Fourth World brings an extensive “drift” of the rules of Dungeon World to play in the high-fantasy “hopeful, post-apocalyptic” setting of Earthdawn. Though originally intended as a light skin of Dungeon World, the game has mutated into something with its own playbooks, revised basic moves, incorporation of Perilous Wilds, much different spell casting and item management, introduction of mounts and vehicles (air-ships, and the like), and replacement of whole subsystems. As an example, alignment has been replaced by a system that uses Earthdawn’s “Passions” in a way that owes a lot to the “icons” of 13th Age.
Like all DivNull Seeds, the game is as finished as I intend to make it, but no more. Sources of the game (e.g. InDesign files, art, etc.) are available, and the game has been released under a Creative Commons license.