Valve Software on Tuesday launched the Mac OS X version of its Steam online gaming platform. Steam, a portal through which users buy, download and play both old and new PC games, was until now limited to the Windows operating system. Valve will soon extend Steam to the Linux platform. Valve launched a collection of game titles Wednesday on Steam for Mac OS X. Additional collections will be unveiled each Wednesday, Valve said. The first collection will include “Torchlight” from Runic Games, as well as “Portal.”
