I remember seeing one good idea, I think it was either here or on 4chan. The basic idea is it takes place after Halloween Ends, and the murders have started up again. A man in Michael's mask is going around butchering people. Everyone saw Michael die. They even burnt his remains and scattered the ashes to the winds. It can't be him. Yet there's this hulking murderer with freakish strength and a refusal to speak. In a sort of purposeful non-ending, no one figures out who it is. No motive is ever given. Once Halloween ends, the killings just stop, and the mysterious figure, The Boogeyman, simply vanishes.