I’m sure you already have enough X-COM copies to build a small fort, but everyone wants me to tell you about this so I’m telling you about it.
Courtesy of Humble Bundle, you can get a copy of X-COM: UFO Defense (UFO: Enemy Unknown) for free until February 1st 6pm GMT: https://www.humblebundle.com/store/xcom-ufo-defense-free-game (activated via Steam)
Tell your friends so they can build a small fort too.