the clown hung him self standing on a block of ice the ice melted and he got hung leaving a clown a puddle and a rope on the ceiling. There is nothing that says the room is locked, that the clown is dead. How about the clown walked into the room and spilled some water and dropped the rope.
If you just have methane in a dark room nothing will happen because nothing is there to react. If the room was light nothing would happen either, as there are still no other chemicals for it to react with.