Valve has announced the first downloadable content for. The currently unnamed add-on will be released this summer on the PC, PS3, Xbox 360, and Mac.'s first DLC will add new test chambers as well as leaderboards for you competitive types. It also adds a challenge mode for single-player and multiplayer, though no details were provided on that. Valve also promises additional unspecified content.One nice feature of this downloadable content is that it's free on all platforms. That's pretty much a given for the PC, Mac and PS3 considering their Steam integration. However, Xbox 360 owners often end up having to shell out money for DLC on Valve games. They'll avoid such a fate this time around.was released on April 19th. Check out our review to learn more about it.