My only concern is if I try and set in history (meaning I would have to throw myself in to a shitton of research, only for me to get annoyed when the PCs end up trying to play as a cowboy or a Fascist) Or if I set it in a hyper low fantasy world.
Another Rp I would love to try is something like the Spanish Civil War, where everyone ends up playing as Hemmingways and Orwells and other expats fighting against fascism.
I just think that it would be really funny if it turned out that Aliya and Madeline were in a totally different village with another group of Glamhoth, while the rest of the group ended up meeting some random NPCs.
When I was reading Seraph's updated post, I did a double take at the mention of a Purifier. Always cool seeing other players pick up and run with your ideas.