Additional content: The additional missions revolve around having to deal with an organisation known as 'EXALT', which are human collaborators with the alien invaders. It's otherwise the same turn-based, third-person, squad based, RPG, save-the-world-from- invading-aliens tactical shooter.
Since this game is an expansion pack of XCOM: Enemy Unknown and I've reviewed the original title here, I'll just use this review as an expansion of my original review! With XCOM: Enemy Within, you get close to the exact same core game as XCOM: Enemy Unknown but with some additional missions and slight modifications of the original game.