An extra-terrestrial force known as "The Outsiders" have infiltrated Earth and are living among the humans. Earth is in many ways being consumed by The Outsiders, and forcing the human population into a perennial state of paranoia; not knowing when or where The Outsiders will strike next, not knowing what they are capable of, and in some cases not even knowing who they are (one class of the enemy is capable of shape-shifting).
XCOM is most certainly back in action.
Closed door demo?
They didn't want the entire public to see how sucky this game is gonna be.
Way to ruin a a good RTS by turning into a mediocre FPS.