I ended up using the old Dark Sun setting as a very loose inspiration point and we did a lot of setting construction through Q&A right at the start. System was basically World of Dungeons with some special ability choices replaced by really evocative playbook moves from across the AW-DW sphere. You know it's going to be a wild ride when one of the earliest things that happens in play in a session is that one character uses psychic manipulation to make a murderous cult leader hand over control of his cult ["the Order of the Emerald Mother"]...to the PC. They agreed to meet at the cult sanctuary in the cliffside tombs that evening to present the 'good news' to the cult. Unfortunately for the players, however, a string of cascading rolls led to a dramatic close-of-session as two characters were hauled away by the city guard for questioning (a PC breaking up an abduction ended up getting fingered for the crime himself!). And the city government is known to be under the control of the cruel order of assassins that the players are probably up against in the campaign front. Will the PCs be 'disappeared' by the town guard, or will they gain their freedom, successfully take over that cult (!??!), and complete their mission to prevent the resurrection of an evil sorcerer-king? I don't know...we'll have to keep playing to find out.
Oh, and one player character is a half-troll Brute who can shapeshift into a pterodactyl. Because reasons.
I may recap the session in more detail in coming days. Very fun times had tonight -- rumbling with a cult, psychic powers, a 'friendly' bout with an old troll rival in the Caravaneers' Arena for Rhetoric and Stick-Fighting, and an attemped rescue of an old ally (who was being carried off in a carpet) - that went terribly wrong...