The reapers have returned from dark space. With Earth under attack and the mass relays in a state of chaos from refugees and the councils fleet engaging reaper forces the galaxy is a mess. The outcome is unknown, the warfare is devastating. The galaxy will never be the same.
With an increasing amount of now ex Cerberus soldiers and scientists leaving the organization, more and more powerful loyalist Cerberus ships are being deployed. But even with so called titan class ships, the ex Cerberus ships and soldiers still fight back. In the fight to protect and save humanity, cooperation with other species is still important.