In the pantheon of video game remakes and expansions, few have achieved the alchemical feat of transforming a great game into an immortal one. Firaxis Games’ XCOM: Enemy Unknown (2012) was a masterful resurrection of a classic strategy franchise, streamlining turn-based tactics for a modern audience. Yet, its expansion, XCOM: Enemy Within (2013), is not merely an addition; it is a philosophical and mechanical crucible that forges the original’s raw materials into a singular, unforgettable testament to the nature of sacrifice. By introducing the volatile elements of Meld, genetic modification, and the morally ambiguous cybernetics of the MEC Trooper, Enemy Within elevates the core conflict from a simple battle for survival into a harrowing interrogation of what humanity is willing to become in order to survive.

If cybernetics feel too extreme, Enemy Within offers a subtler, creepier alternative. Using MELD, you can inject your soldiers with alien DNA, granting them superhuman abilities. These include:

While XCOM 2 (and its expansion War of the Chosen ) exists and offers more refined systems, XCOM: Enemy Within occupies a unique niche. It is the last game in the series where you truly play the defender . You aren't a guerrilla fighter hiding from ADVENT; you are the Avengers. You have the world’s resources (sort of) and the high ground.

: A Sniper with the "Squadsight" ability is arguably the most powerful piece on your board, capable of eliminating threats from the edge of the map.

The cost is high. The soldier loses all previous class abilities and becomes a MEC-class unit. They also lose the ability to wear traditional armor or use cover. But in exchange, you get a unit that can single-handedly hold a choke point.

On the Geoscape (the world map), Enemy Within adds four new secondary research items in the Foundry that are vital for the late game. You no longer just research "Armor." You research specific plating to counter specific damage types.