Ansible is a MOO set in the Orson Scott Card novel, Ender's Game.
Attacked 90 years ago by a race of bug-like aliens set on colonizing the system, an Earth-wide government pulled together its resources to defend humanity. This necessity drove the IF, the International Fleet, to design and construct its 'Battle School'. Located on a space station in orbit around Earth, the school continues to train the brightest and most talented children to be soldiers.
The basics of strategy and space combat comprise the first two years of a student's battle-school life. Upon promotion at age eight, the student takes part in organized zero-gravity war games. Commanders, twelve years of age, lead these armies in battle simulations designed to test the will, mind, discipline, and overall potential of the participants. Graduation from battle school, to a specialized finishing school, occurs at age thirteen.
The IF continuously analyzes its data and intensely monitors its students, seeking the military prodigy that will lead Earth forces to victory. But the timetable is tight, and the war to end all wars nears. The weight of the world rests on small shoulders.