Hamza's already let us know that both DmC and the Alan Wake franchise are reduced this weekend on Steam but that's not all that Valve's service has to offer. Both Primal Carnage and ORION: Dino Horde are free to play this weekend and are reduced in price by 50% and 25% respectively.
If you fancy yourself as an El Presidente in the making, then you should snap up the Tropico franchise which is cut in price by 75% on Gamersgate. Meanwhile, Amazon's Mayhem (Mayhem I tells ya!) Sale comes to a close today, so get your discounts on the likes of Dead Island, Batman Arkham games and Lego Batman 2 whilst you still can.
GOG.com are having a half price sale on classic Activision titles, including the likes of Space Quest and Phantasmagoria. GreenManGaming have a SEGA promo this weekend with different daily deals; right now you can get Sonic and All-Stars Racing Transformed for half-price. I also noticed you can get the recently released Call of Juarez: Gunslinger for 25% off as well. That's all for now but if you find more PC weekend download deals please leave them in the comments.