Microsoft's Games on Demand service is infamous for its non-competitive prices. They often cost much more than current retail prices and seldom even go on sale. That makes this week's Games on Demand sale pretty special. Most of the sale games are pretty old, but their prices have been slashed down to just five bucks in most cases. Plus, the sale includes plenty of co-op offerings. I'm talking about Ghost Recon Advanced Warfighter, Perfect Dark Zero, Tornado Outbreak, Cloudy with a Chance of Meatballs, and Kameo, all super cheap this week.