These bases slowly undermine XCOM operations by stealing your resources, raising the global panic level about the alien attacks, and generally causing extra mayhem. While previously you had to only keep your eye out for oncoming alien attacks, in "Enemy Within" you have to remain wary of other blips on the world map indicating an Exalt base has been set up somewhere on the globe. This adds a fresh level of strategic and tactical depth to XCOM's gameplay. Rather than joining forces with the rest of humanity in the XCOM mission, Exalt wants to get out of the aliens' way, which they do by undermining the player at every available turn. But my personal favorite is a non-alien enemy known as Exalt, which Gupta described as a "paramilitary organization" of humans that met Earth's invasion by alien forces not exactly with open arms, but something of a sideways glance.
If you're a fan of "XCOM," none of these will disappoint. The Exalt enemies might look less exciting than their extraterrestrial counterparts, but the new AI brings a fresh challenge to 2K Games