XCOM: Enemy Unknown is free-to-play on Steam this weekend. Players who participate in the free-to-play weekend will be able to purchase XCOM: Enemy Unknown at 75 percent off, and retain all of their progress.
XCOM: Enemy Unknown is a turn-based tactics game from 2012 and a reboot of the XCOM series. A sequel is in the works. XCOM 2 is coming to PC on February 5, 2016.
The free weekend extends until 10 am Pacific Time on Sunday, September 13.