(Thanks to Midnight Tboy, who highlighted this price in the XCOM 2 thread)
"From the makers of Sid Meier’s Civilization comes a game about civilization’s last stand. As the commander of an elite paramilitary organization known as XCOM, you control Earth’s defenses against a terrifying alien invasion.
XCOM: Enemy Unknown – The Complete Edition includes the Game of Year award-winning XCOM: Enemy Unknown, plus the critically-acclaimed expansion, XCOM: Enemy Within, and all of the released add-on content packaged together for an incredible value.
The Complete Edition Content Includes:
XCOM: Enemy Unknown
XCOM: Enemy Within
Elite Soldier Pack add-on content
Slingshot add-on content
Second Wave add-on content"
Steam says: Metacritic: 88%, Overwhelmingly Positive reviews (95% positive)
The extensive mod Long War is available for XCOM: Enemy Unknown: http://www.nexusmods.com/xcom/mods/88/
XCOM 2, it's sequel, is currently £9.79 :http://www.hotukdeals.com/deals/humble-monthly-bundle-unlock-xcom-2-instantly-9-76-humble-bundle-2594980
And Long War's sequel, Long War 2, is now available for XCOM 2 (17 Jan 2017):http://www.hotukdeals.com/freebies/long-war-2-mod-for-xcom-2-pc-steam-a-must-play-reinvention-xcom-2-released-17-jan-2608284