Today only, Green Man Gaming offers Steam downloads of a mystery game for Windows for $4.99 as part of its 7th Birthday Celebration. Coupon code "FREEGIFT" makes it free. (In cart, click on the "Vouchers" tab to enter the coupon code.) That's a savings of $5 and the best deal we could find. You will receive a Steam download of a random game--it could be awesome, it could be lame, but at least it'll be free.