Maybe the Nightmare aspects don't have to be that difficult to manage or write. I've been thinking about how some of them could have an impact on the bathtub-scene.

A PC has a Nightmare called "Drowning in dark water" - this is how it could affect the scene.

As the PCs approach the woman in the bathtub, the water slowly becomes darker and darker. The woman in the tub is completely submerged and doesn't move until a PC comes close to her; she then starts to move around violently in the water, dragging the closest PC into the water (skill check to avoid drowning). The aspect has been applied to the scene, and will follow the pcs until it is removed. Any scene can now potentially include the themes dark water and drowning. It shouldn't be overdone; the aspect might lie dormant for several scenes, but the GM should note all active Nightmare aspects and apply them only to enhance the action and atmosphere.

As the players move on, more and more Nightmare aspects may come into play, affecting the scenes until a climax is reached or the pcs remove all the aspects.

Other Nightmare aspects could be "What's hiding in those shadows?", "Everybody is lying to me", "Bad things behind closed doors"...

Good ideas, thanks.

I am trying to avoid having the usual insanity stress track altogether, at least in the sense of it being a kind of hit point system. A composure stress track is more than enough.

What I want is to tell stories that include everyday people trying to protect themselves and their families from whatever it is that has pushed people over the edge and into perversion. I'm not even sure that I need the players to really take any more control of the story than what is normal for a FATE game. Maybe I should just leave the "perception becomes reality"-concept to the villains; it would still create some interesting stories.

I was thinking about having a certain kind of aspects called Nightmares. They would describe the fears and unconsciouss beliefs of the pcs, and I would then use these aspects to determine how a situation is experienced. So the concept is based on mirroring; players see what they expect to see, based on their beliefs and mental states (much like in the real world).

Because of this miror-concept, I was thinking of calling the game Dark Mirror or something along those lines...too corny?

Interesting. Is there an in-setting justification for this perspective altering reality thing? Because that could be very interesting long-term if the PCs figure it out...or is it purely a metagame conceit? Either works but it's definitely something you want to think through for a game like this.

Yes, there are in fact several possible explanations for the blurring of perception and reality. Dependant on the players' actions and experiences, one of those explanations will come true. I've written each explanation as if it were the only one, but another point is that even if an explanation is reached, it can still change to something else.

Sounds like you're talking about different tracks of reality. Or at least that's how I'd go with it.

Yes, that describes what I am going for. I have several different narratives that explain what's going on; they're all true, in a sense, even though they are incompatible. It all comes down to what the players find more exciting. An important point behind this concept is the hope that the players use the freedom to choose the pre-determined "reality" of the world they find most interesting.

The idea was simpler in its original form, where the "perception becomes reality"-concept was a tool for me to take the players into the world of the villains - seeing the world as they do, and creating an atmosphere of alienation and feeling caught in someone else's world.

And thanks for the advice on getting players aboard. You're right, the concept does require that the players go all in.

I am playing around with some ideas for my DF game, and I just want to run them by you and hear your thoughts on it.

First, I am planning a campaign that revolves around this little concept I came up with. I want the players to change the story according to what their PCs experience (or perceive) - the basic idea is that perception becomes reality. What the players think is going on determines the storyline. I have some ideas for very open-ended stories, and I want the players to use aspects to create the story they think is going on (it's not a secret - the players know that they control the story).

This sounds more complicated than it is. Let me give you an example of a story that illustrates this idea. A young man is under suspicion for having murdered his wife and sister. The player characters are connected to the family in some way – by proximity, relationships, history or by being witnesses – and so they are drawn into the world of the presumed killer. They discover that he believes his wife and sister are evil beings trying to kill him. He is found in a cheap, murky hotel room downtown, where the body of his sister is discovered in the bathtub, her injuries so severe that she cannot be saved. The young man escapes and leaves behind his dying sister. But instead of seeing an innocent young women lying in the bathtub bleeding to death, some of the characters see the sister as the killer sees her; her eyes yellow and bloodied, fingernails sharp as knives dripping with blood and a vicious smile on her contorted lips. She tries to lure the characters closer, only to let out an inhuman hissing sound and with her last ounce of strength, she tries to bury her nails deep in the flesh of the closest player character.

What happens next depends on how the PCs react, what they see (and don't see). Maybe the sister is just in shock, the attack pure instinct - the players decide what the most exciting story is. This obviously will create a lot of challenges, that's why I am asking for input.

I am also interested in creating a "city" on a small scale to be used as locations for the stories. Instead of a city, it will be a series of "stages" (like a rooftop or an apartment building or a single room). This is of course done in collaboration with the players before the story begins. So the locations will determine where the story takes place. Any thoughts on how to do this will be appreciated.

I have much more to tell about the game, but I want to see if anyone has any thoughts before I elaborate further.

Thanks!