The Games for Windows Website now offers a new Games for Windows client that includes the promised Games on Demand support. They kick off the service by offering the Windows editions of Shadowrun and Viva Piñata at 50% off for a limited time. There is also a GFWL Arcade game called Tinker that's available for free, and word is: "Live enabled World Of Goo and Osmos versions will be coming soon."