[1] Inspired by the 1994 game UFO: Enemy Unknown, gameplay involves the player taking the role of the commander of a clandestine organization known as the Xenonauts, and attempting to defeat an alien invasion of Earth in the alternative history year 1979.

[5] Features advertised by Goldhawk as "enhancements" to the original X-COM model include the following:[6][7] In an alternate history 1958, an alien UFO enters Earth's atmosphere over Iceland and is immediately hostile to the fighters scrambled to intercept it.

Initially, only the smallest UFOs are able to fly in Earth's atmosphere, but the aliens quickly modify their ships to enable incursion by larger vessels.

The aliens attack military and civilian targets in an attempt to spread panic and destabilise Earth's defence.

It was marketed as a Cold War-era based "planetary defense simulator" and as a direct competitor to 2K Marin's The Bureau: XCOM Declassified, which at the time had alienated many fans due to its FPS-based gameplay.

[15] A full release date of the end of that year was announced in September 2013, although the developer conceded that the title might be delayed until early 2014 if additional work was required.

[18] Shortly after the release of the stable version Goldhawk Interactive allowed selected members of the community to access the source code.