The Cadet: Shattered Worlds

In the future, humanity has expanded beyond Earth's solar system into the unknown to establish colonies. This future sees children sent to military academies designed to prepare them to defend the colonized worlds from any threat, both foreign and domestic. When one academy is attacked by an unknown foe, a few surviving cadets flee on the only starship left, and are forced to crash on an unexplored world filled with its own danger and mystery. But the invaders are desperate to track down the cadets before they can warn the rest of humanity, and will stop at nothing to find them.