The Mass Effect media franchise, developed by BioWare and published by Electronic Arts, is set in the distant future where various extraterrestrial species coexist with humanity. The developers created extensive background lore for the universe of Mass Effect and its alien species, with detailed explanations documenting the complex relationships between the universe's various factions and the setting's phenomena from a scientific perspective. The developers were inspired and influenced by numerous fantasy and science fiction works, as well as real world cultural and scientific concepts. Dark energy, a form of energy theorized to massively affect the universe, forms a key part of the franchise's concept and background.
The first three main series games is set in the Milky Way galaxy and follows Commander Shepard, a human special forces soldier who discovers an imminent threat to the galactic community from the Reapers, an ancient collective of sentient synthetic starships which harvest all spaceflight-era organic civilizations as part of a repeating cycle that span millennia in length. The fourth main series game is a standalone sequel about a group of settlers who are members of the Andromeda Initiative colonizing the Andromeda Galaxy. The original trilogy have overall been both commercially successful and critically acclaimed, and the Mass Effect setting has been praised by critics for the believability and depth of its design, lore and narrative themes. The Mass Effect brand has since expanded into a franchise which encompasses a series of novels, comic books, mobile games, an animated film, and a 3D theme park ride, all of which are centered on other characters as protagonists.