
Overlord is a downloadable content expansion for Mass Effect 2. It features four additional missions set on the planet Aite, where an experimental Virtual Intelligence fusion has turned rogue.
Sent on a mission to investigate a Cerberus research facility that has inexplicably gone quiet, Shepard discovers the base overrun by geth. The only survivor, Chief Scientist Archer, delivers a grim warning: an experiment to merge a human subject with a virtual intelligence resulted in a deadly hybrid—a "VI overlord." The rogue AI has already struck three other Cerberus outposts, taking control of all available technology in its bid to escape—and releasing geth across the planet. If Shepard doesn't infiltrate the VI's stronghold and disable it, the malevolent intelligence will transmit itself off-world and cause chaos across the galaxy. The mission spans five new level environments and offers two new achievements.
| PC | June 15, 2010 |
| X360 | June 15, 2010 |
| PS3 | January 18, 2011 |