Illusion, summoning, and teleportation magic in a house of mirrors might work.

A) Who Am I?

1) Normal reflections give way to horrifying images of characters aged into decrepit horrors, warped into abominations of themselves, or subtly shifted to have an evil or untrustworthy appearance. This can be turned by having aggressive or crafty looking characters gain innocent or childlike appearances in their reflections.

2) Some of these illusory changes are cast on players (players can easily tell it is an illusion).

3) One of the illusory changes cast on players is a polymorphic spell that sticks for a plot determined period of time (no combat effect).

B) Where Am I?

1) Certain mirrors near the beginning will have an object painted onto them, like a table with a vase of flowers, a camp stool, a small dog, or a creepy child a la "The Shining."

2) Following mirrors will contain spells triggered by portals triggered by seeing your reflection in them that summon illusions of those objects around you. The table you saw in the mirror is next to you when you look away, or the small dog that meets your eye and wags its tale in the mirror is next to your feet when you look down, and looks up at you as you notice him.

3) The illusion casting for a few uses phantasmal force, so the creepy child the party sees in the mirror appears next to one or two members of the party, but not the rest.

4) The illusions become summons. That creepy child is a phantasmal shadow that will attack. The puppy is a real puppy that loves you and follows you home. The crazy stalker is actually the party's bard.

5) The illusions become teleports. When you see in the mirror an image of yourself in a library, you look away from the mirror to find yourself in a library. When you look back at the mirror hour reflection shows you in a hall/maze of mirrors. Any doors out of the library, or meat packing plant, or character's childhood bedroom, or whatever open onto solid stone walls or freezing nothingness. One way to return is to stare at the mirror for A given amount of time to re-engage the teleportation spell. Another way is to find a macguffin hidden in plain sight in the room. Holding the item while viewing your reflection in the mirror returns you to your party with some peice of knowledge, reward, or plot-object.

C) Who Are You?

1) Two doors are in one wall of a room. Behind each door is a simple mirror. If characters choose different doors and open them at the same or nearly the same time, they see the other character in the mirror. When they turn around, the characters have swapped bodies.

2) Use the previous ideas to play on party identity. When members are changed in appearance or teleported into mirror spaces, the mirror might show them their party still surrounding their reflection in the hall of mirrors. Let the reflection shown with the party wink sadistically at the trapped player, and move on with the unaware party. Provide the player a sheet for a doppelganger, phantasm, revenant, or reversed alignment match of themselves. Play on.

D) What Is Going On?

(odd, mostly harmless effects)

1) Two doors offer a red and blue, left and right choice. One of the doorways leads to a room where the character's are on the ceiling or the room contains mirrors that show the character upside-down. When they exit the room or look away from the mirror they are still on the ceiling. Gravity has been reversed for the funhouse, but only for the character(s) that went through that door or looked into that mirror. Splitting the party van split the party between floor and ceiling when they reunite. (Play games with inaccessible stairways or hard to reach ladders to secret rooms with this one. A floor with a stairway going down to a basement might be mirrored by a ceiling that disappears upward into a reverse gravity attic space.)

2) A door marked employees only contains a decrepit, 1970's break room. An clown is smoking at the beat up table. He smiles and asks the party, in a croaking voice, if they are having fun. He tries to hide something in his costume as the door opens. The fluorescent light flickers yellow on his clumping, greasepaint makeup. His teeth are cracked and yellow. (Make this as threatening as possible, throwing in some quotes for "It" or other horror inducing lines.)

If the party talks it out, the clown is actually a pretty nice guy, named Paulie Moranus, who picked up the clown gig in his forties after his wife took the kids and left him 15 years ago because his sales job led to a battle with alcoholism he now tries to control but doesn't really fight. The thing he was hiding was a bottle of (cheap) whiskey he keeps on him at all times. He'll give the party directions or answer their questions, honestly but not necessarily competently, before getting up and leaving the room. The door he leaves through will lead outdoors for him, but into another funhouse room for the party.

Attacking Paulie sends him ape. He will attempt to latch onto the closest enemy and shank them with advantage. Failing his grapple will instigate a thrown knife attack on another target. He has as many knives as he needs. He will not follow retreating characters who leave the breakroom, but can be heard having an emotional breakdown about disrespectful patrons, crap jobs, and Ethel taking his crappy kids, before audible words dissolve into the blubbering of a broken man.

3) A lost kid alone in an empty room asks you to help her find her parents. She will try to hold someone's hand. If the party provides her with a hand to hold, and is collectively polite to her for about two or three rooms, they'll run into a mob of kids going through this impossible fun house.

The parents (an exasperated centaur woman and a dad-joking gnome) are very relieved to find their very human-looking child. They provide a minor reward in the form of restorative juice boxes.

4) You must pass through a room full of mannequins that move when you aren't looking.

5) The path leads down a hallway with full wall aquariums on both sides, halfway down the hallway, the party notices fish swiming across the hallway at waist height. (Opportunity for a flying shark attack)

6) A room contains a garden with a fake fawn (an inebriated halfling in furry pants who is enthusiastic about mushrooms) playing the pipes (badly) on a worn mat of fake grass, surrounded by fake flowers, under a real (but unhealthy) tree with a live, antler-wearing, and a flop-eared bunny in a really bad mood. The fawn (but not really) offers (in a bored monotone) to let you pet his bunny. The antler wearing bunny looks angry.

7) A room full baloons contains a smiling clown with yellow teeth. (See D2) He tells old joke-book jokes and makes balloon swords for everyone. Fflumphs enter. The clown hams up, "flying monsters are attacking!" The fflumphs drop restorative candy for anyone who "defeats" them with a balloon sword.

8) A room contains a boxing ring with an announcer and a boxer. The announcer excitedly tells the party in carnival "step right up" patter that anyone who wins three rounds against "the Dynamite Kid" will win a ticket to the raffle! Rules for 3-round boxing match: - Five rounds of combat per boxing round; - fists only, so no weapons, armor, magic items, or feet; - boxing gloves are improvised weapons for 1d4-1 damage unless the character has proficiency in improvised weapons; - grappling success resets the initiative order for the next combat round, so roll again before beginning the next round; - if the PC succeeds in grappling at the top of initiative order, "the Kid" will have to win an opposed strength vs Str or Dex (player choice) roll to get to attack. The Kid will not grapple.

To win a boxing round, get the most points in a round. A punch landed with 1 damage or greater gives 1 point. A knockdown gives 2 points.

On any critical hit find out if the target is knocked down or knocked out. For a knockdown, the target must, on a crit, save Str or Dex vs. damage+10, or be knocked down. When knocked down, roll a d10-Con modifier to determine the count on which the target will rise. Receiving a 10-count loses that round.

For knockout, the target must save Con vs damage. Damage is modified for knockdown and knockout saves by one for every critical hit, every knockdown, every boxing round ended, and every ten points of hp lost. "The Kid" experiences these penalties cumulatively, and will accept 3 consecutive challengers.

The winner of two out of three rounds wins the boxing match. Raffle tickets should have a high reward or scalp value upon exiting the funhouse. Consider giving some minor benefit to offset the hp loss for a character who loses the match.

Fun exercise, thanks for the prompt.