Green Man Gaming offers downloads of XCOM: Enemy Unknown for Windows
for $13.59. Coupon code "GMG20-6WUSQ-LBC4U" cuts it to $10.88
. That's $2 under our mention from three days ago and the lowest price we've seen for this game. (It's also a current price low by $2.)
Note that this game requires a Steam account to install and play.