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 galaxy, only a miracle could save them. Then again, Shepard did come back from the dead.
Take Earth Back
Did You Know?
In the DLC 'Citadel DLC' Ashley Williams and Commander Shepard have a drinking contest at the casino bar. At that moment a Vorcha and Batarian walk over to them. This is the conversation they have. [The batarian hits Commander Shepard's arm to get his attention]. Batarian: "My friend doesn't like you Alliance types". Ashley Williams: "Listen dude, we're trying to do something here". [Commander Shepard focuses on the game again. The Batarian hits his arm once more]. Batarian: "I don't like you Alliance types either". At this point Ashley and Shepard get annoyed and beat up the Vorcha and Batarian. This is a huge reference to Star Wars. 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
Leviathan - Leviathan DLC
The darkness cannot be breached.