Believe it or not, the idea of living a fantasy world dates back to the Roman times. Stories like Metamorphoses talked about the creation of the world in 8 AD where science was unheard of. In fact in 2000 BE the first ever piece of fiction writing happened to be of the sci-fi genre. It was named Epic of Gilgamesh. Despite the lack of technology the story had many of the features of a modern sci fi story such as post apocalyptic scenes