Wikipedia
X-COM (sometimes stylized as X-Com ) is a science fiction video game franchise featuring the titular fictional elite international organization tasked with countering alien invasions of Earth. The series began with the hit strategy video game UFO: Enemy Unknown created by Mythos Games and MicroProse in 1994. The original line up by MicroProse included six published and at least two cancelled games, as well as two novels. The X-COM series, in particular its original entry, achieved a sizable cult following and has influenced many other video games; including the creation of a number of clones, spiritual successors, and unofficial remakes.
A reboot series entitled XCOM was published by 2K Games, beginning with the strategy video game XCOM: Enemy Unknown, developed by Firaxis Games and released in 2012 to critical and commercial success, with an expansion to Enemy Unknown, called Enemy Within, being released in 2013 alongside a prequel, The Bureau: XCOM Declassified. A sequel, XCOM 2, has been released in 2016.
X-COM (also X-COM: First Alien Invasion) was part of a budget range video game series released in 1999 by Hasbro Interactive for Windows that relied solely on the Play by mail concept.