Les Enfants Terribles by Jean Cocteau
A tragedy about the power of the imagination and the strange, claustrophobic world of childhood. At home, Paul shares a private world with his sister Elisabeth, a world from which parents are tacitly excluded. Their room is where the Game is played, the Game being their own bizarre version of life. All that they do outside is effectively controlled by the rules of the Game -- but unfortunately the rules of the Game prescribe that two children must die.