Your planet has been invaded by hostile forces. The only chance for success is to draw troops from a handful of courageous and face the enormous odds. Strategically deploy various task forces to invade the enemy back and thus put an end to its dominance. Troops attack in waves, and thus giving you ample time to upgrade your own weapons. The greater success is achieved more quickly if you assemble a strong army. But remember, it is of utmost importance to defend base which houses the power plant. Without the needed energy would not be able to operate machines and usurpers would very quickly won. With each victorious battle, not only are increasing your chances of liberation planet, but also to build more efficient plants.