Pandora's Star Adventure

The starship, named the Second Chance, is launched for Dyson Alpha. Several months later it arrives. As soon as it does so, the massive barrier containing the system vanishes. An incredibly hostile and well-armed race attacks, with the Second Chance barely able to return to safety. The Prime are free, and they know the location of the Commonwealth. Only 7 months later, wormholes open above twenty-eight planets, and thousands of megaton nuclear warheads are launched trough. The few defense systems you possess are ineffective, as planet after planet falls to the Prime. Humanity goes extinct.