The truth is, XCOM still exists, though it's become a shadow of its former self after world leaders and bases either surrendered or were destroyed. Reduced to a covert guerilla military operating in cells around the globe, this new "Resistance" has more than the standard aliens of the original game to contend with. Those monsters are back and scarier than ever, along with entirely new creatures - but it's the humans who serve the aliens - known as the ADVENT - that pose the most insidious threat...