Just posted this in the Feaocder (?) thread and will paste it here for the sake of completion:
Game idea:
You play a ghost/ demon and have to run from human beings with flashlights (you can see their cones) and you can only kill them from behind/ if they don't see you, this should be suspenseful enough if done right. To reduce the amount of work that goes into level design you could build a 2/3 floors high mansion where the ghost/ demon lives in and wave after wave more people (that want to see/ hunt/ kill the demon) enter the building from different doors and windows.
Alternatively this could be extended to open air levels (woods) or tunnels and dungeons, obviously with or without wave-based gameplay.