it must be original. It can't share plot elements of any previous book or movie.
Hunger Games = Running Man
Avatar = Pocahontas
Psion Beta = Enders Game
Harry Potter = Some previous good novel CavemanCougar read
I find the notion that a book must be 100% original silly and I'll continue to enjoy retold stories with interesting twists or imaginative new worlds.
Thank goodness the BBC remade Sherlock even though I know the stories, it is one of my all time favorite shows.