Ender’s Game is one of my favorite Sci-Fi novels. It is about an imminent alien invasion that Ender is supposed to stop. The cool twist in the story is that he doesn’t know what he is doing. He is made to believe that he is playing a training game: a simulation fighting the aliens.
Andrew Wiggins (Ender) is taken from his family when he is just a boy. He is trained by the military to fight the aliens. He quickly rises through the ranks to become commander. He shows exceptional skill at winning all the games.
He is made to believe that he is playing a simulation game against the aliens. He wins by strategic maneuvering. He is happy because he thinks that he has successfully completed his training. It is at this point in the book that Orson Scott Card delights the readers.
When the game is over, only then Ender is told that the whole thing was real. He is furious because he finds out that he has unknowingly committed xenocide.
It is self-inflicted retribution that Ender becomes the loneliest individual in the universe. He finds out that the aliens had been trying to contact him using telepathy. Then he learns that the aliens have left an egg. He makes it his mission to undo what he did by populating a planet with these aliens.