XCOM: Evolution

XCOM: Evolution is an expansion for XCOM: The Board Game 
 that complicates your war effort with new missions, enemies, and
invasion plans, as well as mechanics that make your struggles more
dangerous than ever. As the alien forces spread and peril increases, the
sinister humans of the EXALT seek to take advantage of the chaos to
infiltrate and destroy XCOM from within. Their treachery leads to new
challenges, and you'll face new crises, you'll find your work subverted,
and you'll have to deal with new threats to the very resources you need
to win the war.

Fortunately, your team has also made some advances since the war
began. The discovery of the mysterious alien substance known as Meld
promises to unlock some astonishing breakthroughs in the field of
biomechanics. And XCOM: Evolution allows you to pursue some of
these advances, potentially bringing formidable new weaponry to the
field in the form of MEC Troopers!