The game is DLC on PC and Mac, meaning the player needs Enemy Unknown in addition to Enemy Within to play. In an interview, Garth Deangelis, producer on Enemy Within, said that the expansion could be seen as a 'Director's Cut' to Enemy Unknown. Enemy Within featured the same story progress of the same invasion from Enemy Unknown, but added more features, units, abilities, resources, and maps.
It is a expansion pack to XCOM Enemy Unknown. XCOM Enemy Within was announced on August 21st, 2013, with a release date of November 12th that year.
