Green Man Gaming takes up to 90% off a selection of game downloads for Windows, Mac, and Linux during its Black Friday Sale. (Sign in to see these prices.) Plus, coupon code "BLACKFRIDAY10" cuts an extra 10% off. Better yet, all orders will be bag a mystery game download for free. (Your bonus key will be delivered along with the game you ordered.) A couple of best bets, with prices after coupon: