I've been playing Fallen London for quite some time now, and thought that it's dark whimsy might lend itself to a few interesting stories. The concern, of course, is that the Neath isn't quite as real as the world above. Death isn't often permanent, things move behind the mirrors and those trapped in the pierced heart of the fallen fifth city tend to shift between dream like fugue and horrible reality.

TV Tropes has a bit more information, but just think of the 'Neath like the Asphodel Meadows - only it can be reached via a channel system from the sea above, has a thriving trade business with the rest of the world, and a literal railroad to Hell's republic for the unwary soulless who gave in to devilish temptation. Spend too much time down in the haze and even sunlight becomes deadly to your shaded spirit.

What system would be best for this sort of setting, where whispers can hold power and gossip is a weapon? I was thinking FATE for flexibility, but that seems off. For a quick start, what about LASERS & FEELINGS? It could be adapted to a Zubmarine campaign pretty easily. Or Ghost/Echo, which I've always loved as a starting point for a variety of odd ball games.

Have you ever run anything akin to this? What system would you suggest?

I was considering either Savage Worlds or Powered by the Apocalypse, depending on whether the campaign would concentrate on action or story.

FATE is a damned good choice based it's flexibility and narrative play.

If you know enough about FFG's narrative rpgs, those could be adapted easily to fit this genre, I only know Star Wars and L5R, but Grimm (Brothers Grimm fairytale setting) or Fireborn (modern day London with returning magic) look like neasr perfect fits and the generic Genesis system is made to be shaped into what you need.