Orson Scott Card, Xenocide: Children of the Mind

He is the greatest of the space age commanders, the executioner who wiped an entire civilization from the face of the universe, the man whose name has become synonymous with cruelty on all inhabited worlds - Ender Xenocide.
He is Andrew Wiggin, Speaker for the Dead, savior and peacemaker.
Ender's great game is nearing its conclusion. But before he emerges, he must endure many trials. A punitive fleet seeks to destroy Ender's home planet—the rebellious Lusitania, where three intelligent races struggle to coexist, and the deadly descolada virus successfully overcomes all attempts to control it. Danger also looms over Jane, Ender's longtime friend, who lives in the ansible network. And time is slipping through one's fingers...
It would seem that against such a bleak backdrop, there's little room for hope for a better future. But as long as the rational principle that gives meaning and form to everything in the Universe remains, the game will continue.