Master of Orion II: Battle at Antares

Long before the time in which the game is set, two extremely powerful races, the Orions and the Antarans, fought a war that devastated most of the galaxy. The victorious Orions, rather than exterminate the Antarans, imprisoned them in a pocket dimension before departing the galaxy, leaving behind a very powerful robotic warship, the Guardian, to protect their homeworld. Some time after the game starts, the Antarans, having broken out of their prison dimension, begin to send increasingly powerful...