Earth is under attack by a monstrous race of gigantic living ships known as the Reapers. Even if Commander Shepard could unite all surviving species in the universe, only a miracle can help. Then again, Shepard did come back from the dead.
Did You Know?
The game's ending received such a negative reception that the development studio postponed all planned Downloadable Content to develop and release the free "Extended Cut" DLC, which expanded upon the original endings. See more
It's stated in Mass Effect 1, as a major story of the Mass Effect 1 game, that the Citadel is a giant mass relay used by the Reapers as an entry point to the galaxy and that the Keepers of the Citadel are altered by the Protheans so they ignore the Reapers control signals, making their return impossible. However by the end of Mass Effect 3 the player learns that the Catalyst, who controls the Reapers and also the Keepers (who at this point in game are serving the Catalyst in processing the human bodies) is housed on the Citadel itself. That revelation makes the existence of Mass Effect 1 plot useless. See more
In our cycle, we would remove their limbs one by one and offer them a choice: eat their own flesh or starve.
References The Hunt for Red October