In case you haven’t seen Dark City (1998) you really should go watch it. You also shouldn’t read anymore of this post first because it will have spoilers.
So first of all Dark City is a bit like The Matrix. Except instead of the main character knowing about the concept of the Matrix, and then discovering it the details throughout the movie, the protagonist in Dark City wakes up in a bath tub, confused and alone, and we as viewers slowly unravel the mystery of his world. The plot seems to be mostly about solving a murder, but really he uncovers the horrible truth that he’s trapped aboard a giant lab where alien creatures test on humans in an ever changing city. There are cool hints to watch for on subsequent viewings, great atmosphere and art, and overall a really mind bending idea.
I’d like to a similar concept with Fickle RPG. I’d frame the one-off/mini-campaign to the players as a standard detective story. I’d say maybe 1920s era to them, and that they’d be trying to solve a mystery. But as they dig through the plot elements and story they start to uncover things that can’t be true. Like who are these strange looking men shuffling around at night? What is this empty injection they find near a sleeping vagabond? Why can’t they leave the city? And slowly the plot would continue and they’d end up at the big reveal.
I think this is a fun idea because it throws a lot of player assumptions out the window. Like “I know the rules of this universe”, and “a city in 1920 can’t suddenly change”. And it’d be a bit of a test of my GMing skills to keep a straight face as they start to realize not everything is as it seems. I’d also have to work really hard to make sure they got the right clues (the old “give 3 clues when you want the players to find 1”) to make sure the story continues at a good pace and is revealed without my standard weakness of a giant exposition dump.
I could see a similar style game in the Cthulhu mythos, where the characters are digging into a crime in a small town, and discover cultists, and oh wait the cultists actually have summoned some dark, fantastical creature.