The White Wolf World of Darkness roleplaying game Changeling: The Lost has been out for about a year. I think it's the best one of the new WoD games which I have read (Mage, Vampire and Werewolf are the ones I've looked at). It has the most horrifying set-up: the player characters are people who the Faeries have abducted and who have escaped from torment back to this world, only to discover that they haven't been missed. (Basically. There can be twists.) This is much more a personal horror for me than discovering that you can either shoot out fire out of your fingertips, change into a wolf-monster or continue going about even after death.
What I really like about the game is, again, its toolbox nature. There are more options than in many games even when playing by the book, and the game (with four supplements this far) is written to encourage changing things and exploring. I have gotten many ideas for Changeling games, most of them modifying the background quite much, but they would in my mind be still Changeling.
One of the ideas I would like to run one day is this: Move the whole setting to a more 'traditional' fantasy world. Pseudo-middle ages or so, like in most fantasy rpgs nowadays. Ditch most other supernaturals in the nWoD mythology - mages could perhaps stay but with background as something completely different. And here's the catch: make the knowledge of the Hedge and Arcadia if not fully public, at least semi-public. The common masses know that there's something out there which captures people. Some of them come back, but somehow changed. The returned people can recognize each other, but ordinary people can't, except perhaps with some magic (hence the mages, to give an opposition).
Also, model the mortal society along the lines of the Faerie courts described in the game. Perhaps there could be seasonal courts, with each ruling a fourth of the year, perhaps the courts rule different areas. Or you could pick the night and day courts, with each ruling during its respective time. Mortals probably wouldn't trust the returned people that much, but they would be valuable anyway with all the contracts they can use. The Hedge would come in handy, too. The mortals would have access to the Court Goodwill traits but obviously not Mantle.
My idea is that then you would have a real scary conflict. Everybody knows what's at stake and how tough the enemy is. The society would have to depend on the returned changelings, but could never really trust them. Probably the society needs some thinking so that changelings don't just rule all of it. I really would like to add mages, with a somewhat conflicting agenda - perhaps they would like to try to communicate with the True Fae?
Lots of possibilities for intrigue, both with mortal courts and the Fae parts. Also the mages would add a complication. You might also have a more action oriented campaign, with battles in and out of the Hedge, with mortals helping.
Today we played the first session of a more 'traditional' Changeling game. It was fun, although the characters are a bit vague, still. We just discovered that some of the people we knew before our capture (38 years earlier) are still alive...
(Oh, and
heron61: a while ago you talked about how strange it is to write about a book you've read when you know that the author reads the text. Same to you, really. Not that I mind, it really is strange realizing it.. :)