20 years have passed since world leaders unconditionally surrendered to alien forces and XCOM, the world's last line of defense, was left destroyed and scattered. Now the aliens hold dominion over the Earth, building shining cities that promise a brilliant future for humanity on the surface, while hiding a sinister intent below and eliminating all who don't fall in like with their new order. Online those who live a the edges of the world have a modicum of freedom. Here, a force gathers once again to stand up for humanity. Consistently on the run, the remnant XCOM forces need to find a way to regroup, expose the nefarious truth behind the occupation, and eliminate the alien threat for good.