Mass Effect 2 is an action role-playing video game developed by BioWare and published by Electronic Arts for Microsoft Windows and XBOX 360 in 2010, and for PlayStation 3 in 2011. It is the second installment in the Mass Effect series and a sequel to the original Mass Effect. The game takes place within the Milky Way galaxy during the 22nd century, where humanity is threatened by an insectoid alien race known as the Collectors. The player assumes the role of Commander Shepard, an elite human soldier who must assemble and gain the loyalty of a diverse team to stop the Collectors in a suicide mission. With the use of a completed saved game of its predecessor, the player can impact the story of the game in numerous ways.
For the game, BioWare changed several gameplay elements and put further emphasis on third-person shooter aspects, including limited ammunition and regenerable health. In contrast to the exclusive focus on the main story of the original Mass Effect, the developers opted to create a plot where optional missions had as much intensity as the main mission. Mass Effect composer Jack Wall returned to compose Mass Effect 2's music, aiming for a darker and more mature sound to match the mood of the game. Mass Effect 2 also supports a variety of downloadable content packs, ranging from single in-game character outfits to entirely new plot-related missions. Notable packs include Kasumi – Stolen Memory, Overlord, Lair of the Shadow Broker, and Arrival.