Mass Effect 2 is an action role-playing game developed by BioWare and published by Electronic Arts for Microsoft Windows, Xbox 360 and PlayStation 3. The game was released for Microsoft Windows and Xbox 360 on January 26, 2010 and for PlayStation 3 on January 18, 2011. It is the second chapter in the Mass Effect trilogy of video games.

Gameplay in Mass Effect 2 is influenced by decisions from the original Mass Effect. Many aspects of the game have been changed and refined, including a complex inventory system and the removal of both the Mako and long elevator rides. Conversations with the A.I. have been given a more cinematic touch and players are now able to use a context-sensitive interrupt system. In combat, players now have ammunition and regenerable health.

After the events of Mass Effect, the Normandy is attacked by an unknown starship and Commander Shepard is killed. Shepard's body is recovered and he/she is brought back to life by Cerberus, a human supremacist organization led by the Illusive Man. Shepard eventually learns that the Reapers were responsible and working by proxy through an insect-like species called the Collectors, and that they are responsible for entire human colonies disappearing throughout the galaxy. Shepard must recruit and gain the loyalty of a diverse team in order to defeat the Collectors in a suicide mission.

A critical and commercial success, Mass Effect 2 shipped over two million copies worldwide in its first week of release, and has received universal critical acclaim. It is currently the third best reviewed game for Xbox 360 and the 14th best reviewed game of all time, according toGameRankings. The game holds over 70 perfect scores and has an average score of 96 for the Xbox 360 and 94 for the PC and PS3 onMetacritic. In July 2011, IGN named Mass Effect 2 the best game of the modern console generation (2005 - present). In 2010, the game was included as one of the titles in the book 1001 Video Games You Must Play Before You Die.