Ender's Game

In order to develop a secure defense against a hostile alien race's next attack, government agencies breed child geniuses and train them as soldiers. A brilliant boy, Andrew "Ender" Wiggin lives with his kind but distant parents, his sadistic brother Peter, and the person he loves him more than anyone else, his sister Valentine. Peter and Valentine were candidates for the soldier-training program but didn't make the cut. Ender's skills make him a leader in school, where children play at mock battles in zero gravity. His psychological battles include loneliness, and fear that he is becoming like his cruel brother. Is Ender the general Earth needs?