The central theme, of how to combat enemies and rivals, is underlined by the peaceful resolution; but the other important theme, that of kinship and family, is reconciled by the relationship between Ender and his sister, bot at the beginning of the novel, when they team up to combat their big brother's cruelty, and by their swimming scene when Ender is on leave.
The Enders Game is a short story written by Orson Scott Card that was later expanded into a novel and turned into a cinematic movie. Within the short story the focus is on the main character, Ender, who leads an army fighting a unidentified enemy. Within this story the soldiers who are fighting are children who have been trained and are overseen by adults. During the course of the story the children believe that they are playing a simulation, or game, on how they could defeat the enemy however at the end they find out that the situations they battled were real and that the choices they made have real world implications.