Green Man Gaming offers Steam downloads of Sid Meier's Civilization: Beyond Earth for Windows, Mac, or Linux for $19.99. Coupon code "DEALNE-WS25OF-FEXCVC" cuts it to $15. That's a buck under our mention from two days ago and the best price we've seen. (It's also a current low by $10, although most stores charge $50.) Deal ends May 1.