No Flag, No Country

Imagine a pulp adventure setting like Indiana Jones dropped into a late medieval-ish fantasy world. Nations jostling for position in time of political and theological turmoil, agents of Guilds, governments and crooks competing and cutting deals over ancient treasure and knowledge in a lost continent. All PCs have come to the Islands ostensibly as a representative of one of the major political powers. You have goals your faction wants to accomplish, and can choose to work on those or pay lip service and pursue your own cause. You could loot ruins for setting history and treasure, take advantage of a portal to the Beyond for study of theology or Demons, or try and keep the delicate balance of peace in a bar full of PCs (good luck with that last one).

The setting's a "medium-sized fish in a small pond" one about personal victories. The PCs are trusted agents of the various factions, and are given goals on an individual basis. It is not a game based around direct, major conflict between PC groups. If half a dozen players are playing Guild of Magics PCs, that doesn't mean the Guild of Magics sent the most people. It just means a few of their many agents go and poke the portal a lot on Fridays. PCs don't have enough power to make their faction "win", but they have enough to help it score some points.