Portal 2, the sequel to the acclaimed first-person shooter included in Valve’s Orange Box collection, is headed to Mac, PC, and Xbox 360 this fall; the news was confirmed by scans from the April 2010 issue of Game Informer magazine. Unfortunately, the forum thread where the scans first appeared has been overloaded, leading to “Photobucket bandwidth exceeded” messages, but one image has been reposted in several places online.

Confirmation from Game Informer magazine

Meanwhile, a reader of The Unofficial Apple Weblog confirmed that the same issue of the magazine confirms a May launch of Steam for the Mac. Based on teaser images sent to various web sites last week by Valve, that part of the news was all but certain – it remained to be seen which, if any, of Valve’s games would head to the Mac too.

That person quoted the Game Informer article as saying: "Valve will start a beta program this spring, with a full launch targeted for May [...] If you already have a Steam account but want to use it on your brand-new Macbook, for instance, your Steam keys will still work." Anecdotal evidence suggests that many Mac owners have been using Steam on Windows via Boot Camp, so that quote confirms they won’t have to buy the same games twice, which also means that Valve must be porting its titles to the Mac.

Game Informer’s web site has confirmed that Portal 2 will be the subject of its April 2010 cover story, noting: “Among Valve's stable of popular shooters, one game stands alone: the mind-bending puzzler, Portal. A small-scale experiment that was squeezed into 2007's The Orange Box alongside some powerful heavyweights, the love Portal received from fans was beyond anything Valve could have imagined, winning it a full-fledged, standalone sequel.” The site doesn’t so much as hint that a Mac version is in the works, but Game Informer has set up a Portal 2 hub page where it will post supplementary features throughout the month of March.

This move by Valve is similar to Telltale Games’ recent decision to port its catalog to the Mac and allow anyone who had purchased the PC versions to download the Mac ones for free.