Note: This idea is based off the premise for a mange/game called Corpse Party. You don't need to have heard of it or seen it for this idea, but if you have, you'll have some idea of the type of thing I'm looking for... So onward!
It was supposed to be a fun after-school game. Something that they would chat about in the holidays and laugh at how seriously some people took the paranormal stuff people can find on the internet. A simple charm to supposedly summon a spirit of the dead, a spooky and silly affair that none of them believed would work and they set about lighting the candles, writing the talismans and sitting in the required positions with smiles and amused chuckles. The chant was spoken as a joke, ghostly sound effects provided by a CD playing in the corner of the classroom the group used... But once it was finished, everything changed.
A crack appeared in the wooden floor, pitch black visible beneath and as the students hurried to try and leave the doors simply wouldn't move; as if they were painted to the walls. The crack widened and split the room until the students fell down and into the seemingly endless dark, into God only knew what awaited them...
One of the group, a young boy (me) slowly comes to his senses with a low groan and drags himself shakily to his feet. Immediately he knows something is wrong; windows are cracked and show only blackness outside, the classroom he's standing in has decayed over years with dust clinging to every surface. Some desks are cracked, holes in the floor and the flickering lights above offer nothing in the way of comfort. Worse still... He's completely alone.
Panic takes him and he runs from the room, shouting for anyone who might hear him. The school is clearly old, the smell of grime stinging his nose as he runs until his breath leaves him and he has to stop, heaving against a wall. No one answers his call and he groans, having no idea what's happening or where he is, when suddenly he sees a figure reflected through the dirty window of the classroom next to him. A scared smile comes to him and he hurries into the room, thinking that he won't be alone. He flings the door open and looks across at the person only to scream and stagger backwards.
It was a person, but he's long-since dead; his neck slightly stretched from the noose tying him to a beam on the ceiling...
I'd like to go from here, with my character's scream drawing attention. Your character could be another classmate, a ghost, another survivor from another group... Its limitless. I'd want your character to somehow end up being twisted by the building or the spirits into something evil, something that will attack my character and subject him to God knows what.
You could even play the school itself if you wanted... Its all up to you. You could start off friendly, making a slow descent into madness? You could already be a malevolent spirit... Its all up to you.
Please PM with interest!