On the other thread, I was talking about Small note passing between GM and PC, and let me tell you the way it lead to TPK.
Context, horror one-shot, occurring in space-ship, with PC agreeing on PvP option (As they said It's a one shot anyway, let's have fun). I started to introduce some hallucination, at the beginning it was just stuff like not consistent between what they see and what the clue says, but quickly, I started to give inconsistent information to the PC through small notes, letting the Paranoia grew until they were sure there was a traitor amont them. Now imagine, the PC lost in space, inside a haunted space-ship starting to fight each other.
Obviously it finished by a TPK, which for an horror oneshot is a great result