XCOM: Enemy Within is an expansion pack for XCOM: Enemy Unknown , a turn-based tactical strategy game. The expansion adds the ability to gene mod soldiers, allowing them to have new powers, as well as the ability to create MECs, powerful robotic soldiers.
The expansion also introduces a new resource called Meld on the tactical battlefield, which can be used to collect and craft these new features. New maps were added to the game, along with multiplayer options. The PC version requires the base game, while the Xbox 360 console version is a standalone game that includes all Enemy Unknown DLC.
The gameplay in XCOM: Enemy Within builds upon the original game's turn-based tactical strategy, adding new layers of complexity and depth. The addition of gene mod soldiers and MECs requires players to think strategically about their soldier's abilities and deployment on the battlefield. The resource system adds a new layer of management, as players must balance the need for power upgrades with the need for resources.