Nvidia Shield-exclusive Android versions of both Portal and Half-Life 2 launched today on the Google Play Store for $10 apiece, the fruits of a partnership between Nvidia and Valve. Back in March Nvidia announced plans to port Portal to the Shield, Nvidia's Android-powered handheld game console, but never gave a firm date for launching the game or acknowledged that an Android version of Half-Life 2 was also in the works. The announcement was made by Nvidia CEO Jen-Hsun Huang during the company's annual GPU Technology Conference in San Jose, who also said that the Valve-approved port work was done entirely by Nvidia engineers and that -- while both games are only playable on Nvidia's Shield console for the foreseeable future -- there is no technical reason why they could not eventually be released for other Android devices. Gamasutra has reached out to representatives of both Nvidia and Valve for further comment on the launch and more information about the port process.