The XCOM Squad is a reference to the videogame XCOM: Enemy Unknown, which was also developed by Firaxis.

The unit image displays soldiers carrying the Heavy Plasma weapon. This is an energy-based weapon and does not fire projectiles. This weapon defends these soldiers in place of guns that leave behind metal slugs which would potentially rupture the hulls of space craft. Their armor is loosely based on the Titan Armour. Interestingly, the armour required extensive research of alien technology, and the weapon itself was created and designed by the aliens in question - despite there being no such alien invasion in the Civilization world (yet).