Something in the vein of Planescape or similarly-themed setting that involves geography as a manifestation of morality, a permeable reality based on ideas and faith and a sort of Van Gogh, Salvador Dali or Hieronymus Bosch aesthetic.

Heck, maybe a 'normal' world being turned into that realm where the reality is linked to things that are, in a normal setting, abstract rather than tangible and where ideas are given physical representation. The resulting ideological conflict, of course, becomes more acute in such a scenario.

[b]Edit:[/b] Necro'd.