The original trilogy largely revolves around a soldier named Commander Shepard, whose mission is to save the galaxy from a race of powerful mechanical beings known as the Reapers and their agents, including the first game's antagonist Saren Arterius. The first game, released in 2007, sees Shepard investigating Saren, whom Shepard slowly comes to understand is operating under the guidance of Sovereign, a Reaper left behind in the Milky Way 50,000 years before, when the Reapers exterminated all sentient organic life determined to have met or exceeded a threshold of technological advancement in the galaxy as part of a recurrent cycle of genocide for an unknown purpose.
