The story takes place six months after a mysterious alien threat was first detected on Earth. The XCOM team, composed of highly trained soldiers and scientists, is tasked with defending the planet against the extraterrestrial menace.
The gameplay involves tactical turn-based combat, where players control a team of soldiers as they attempt to eliminate the alien threat. Players must strategically allocate resources, assign tasks to their soldiers, and make tough decisions that can affect the outcome of missions.