XCOM: Enemy Within

XCOM: Enemy Within is a standalone-purchasable expansion for Firaxis Games' XCOM reboot, XCOM: Enemy Unknown, which in 2012 brought the series back to its tactical roots after years of action-oriented spin-offs. Enemy Within doesn't rewrite the base game but significantly expands it with new content that changes how players build and upgrade their squad against the alien invasion, while also deepening the decisions between individual missions and strategic planning at the level of the whole campaign.

The most notable addition is the EXALT faction - a secret human organization collaborating with the aliens, against whom the player runs a parallel campaign full of espionage and sabotage, including special missions focused on uncovering its agents. Soldiers can now be genetically modified for special abilities, such as holding their breath or enhanced perception, or alternatively converted into heavily armored, remotely piloted MEC units - both paths bring entirely new tactical options to the battlefield that the base game didn't have. A new resource, meld, was also added, which players have to collect quickly right during missions before it explodes, changing the pace of individual battles and forcing players to take risks for the reward instead of safely retreating to the evacuation zone.

The expansion also brought new maps, enemies, and base improvements, so it functions as a considerably larger and deeper version of the 2012 experience, not just a cosmetic add-on. For many players and reviewers, Enemy Within became the definitive way to play the XCOM reboot, and as a result many later releases offer it bundled directly with the base game in a single package titled XCOM: Enemy Within, as a complete edition for new players.

Why play it: Enemy Within is ideal for players who enjoyed the tactics of the XCOM reboot and want a deeper soldier customization system, a longer campaign, and tougher decisions about where to invest the base's limited resources.