XCOM: Enemy Within is an expansion pack for the turn-based tactical strategy game XCOM: Enemy Unknown. Released for Xbox 360, its genre blends tactical role-playing with base management and real-time strategy elements. Players command an elite multinational military organization, defending Earth from extraterrestrial invasion. They must manage resources, research alien technology, upgrade their base, and deploy squads to combat missions. This expansion adds new abilities, upgrades, weapons, enemy types, and a new resource called Meld, further enriching the acclaimed strategy experience of the core game.