Mass Effect 2 (2010)
The first story, "Mass Effect," in the trilogy centers on a player-created character named Commander Shepard, with the mission to save the galaxy from a race of mechanical beings known as the Reapers and their followers, including Saren Arterius. "Mass Effect" sees Shepard facing Sovereign, a Reaper left as a vanguard, who plans to allow the Reaper fleet currently hibernating in extra-galactic dark space to invade the Milky Way, and destroy all sentient organic life, continuing a mysterious cycle of destruction. The second story, "Mass Effect 2," takes place two years later, and sees Shepard battling the Collectors, an alien race abducting entire human colonies in a plan to help the Reapers return to the Milky Way. The final stroy, "Mass Effect 3," of Shepard's trilogy centers on the final battle against the Reapers.
"Mass Effect 2" is set within the Milky Way galaxy during the 22nd century where interstellar travel is possible through the use of mass transit devices called Mass Relays, a technology claimed to have been built by an extinct alien race known as the Protheans. A conglomerate body of governments known as the Citadel Council controls a large percentage of the galaxy and is responsible for maintaining law and order among races of the galactic community. Races that belong to the Citadel Council include humans, asari, salarians, drell, and turians. Other alien races seen in the game include the reptilian krogan, the environmental suited quarians, and a hostile race of networked artificial intelligences called geth.
During the events of the original "Mass Effect," a geth army attempted to open a portal for a highly advanced machine race of synthetic-organic starships known as the Reapers. It is believed that the Reapers eradicate all organic civilization every 50,000 years. The galactic community has since lived in fear of another possible invasion. Meanwhile, a pro-human organization called Cerberus believes that humans deserve a greater role in the galactic community and supports the principle that any methods of advancing humanity's ascension are entirely justified, including illegal or dangerous experimentation, terrorist activities, sabotage, and assassination. As such, the Citadel Council has declared Cerberus to be a terrorist organization and will prosecute Cerberus agents accordingly. ...
Did You Know? In "Mass Effecg 2", when checking in at the Citadel for the first time, Captain Bailey mentions that "spending a year dead" is a common tax dodge. This is a reference to the book "The Restaurant At The End of the Universe" by Douglas Adams, where a famous band manager is spending a year dead for tax purposes.