I have a couple of ideas! Figured I would post them here.
Idea #1: The player is a ghost who has been summoned by a Ouija board. They must answer the group's questions and choose whether to become at peace with their death, or refuse to and go all poltergeist on them.
Pie in the Sky version: If I were skilled at anything, I might play around with making an interactive Ouija board in which the ghost would move around the Planchard after each question is asked. The player could have the freedom to answer how they wanted, though only a couple of answers would really work. There could also be voice actors to ask the questions.
What we would probably get: A quick choice based game in Twine in which there are a few dialogue trees to choose from. Possibility of voice actors used still.
Idea #2: More ghosts! The player is a ghost (I am a bit too obsessed) in which they have to choose how to best haunt the ghost hunter currently in their space. They can choose which type of ghost to change into and what scare tactics work best (jump scares, atmospheric, poltergeist). Depending on what you choose (or don't choose in some cases), the ghost might be able to find out about their past.
Have a couple more less concrete ideas I won't post here for now. But it's a start!