Valve’s Steam platform began life on Windows, and only just moved to Macs in 2010. Now the Washington-based developer is ready to move Steam onto the wild west of operating systems – Linux.

Valve announced that the Steam for Linux closed beta went live today. The company said that over 60,000 Linux users signed up in the first week alone, and the first round of beta users has been already pulled from the initial applicants.

The one game available to all beta testers from the start will be Team Fortress 2 as its free-to-play. There are two dozen other games available, and users who already own those titles on PC or Mac will also have them available on Linux. Users will also be able to take advantage of Steam’s Big Picture mode which changes Steam into a TV friendly interface.

“This is a huge milestone in the development of PC gaming,” according to Gabe Newell, Valve President and co-founder. “Steam users have been asking us to support gaming on Linux. We’re happy to bring rich forms of entertainment and our community of users to this open, customer-friendly platform.”

Frank Crockett, a member of the Steam for Linux team, notes that Steam will first only be available on the Ubuntu distribution of Linux. He notes that an “overwhelming majority of beta applicants” are running Ubuntu, but other popular distributions are not out of the question. He says that Valve will prioritize development of other distributions based on user feedback.

As for future rounds of the closed beta, Valve says that future participants will be chosen among survey respondents. This will continue until the folks at Valve see “a solid level of stability and performance across a variety of systems.” Once that’s achieved, Steam for Linux will enter into open beta for all.

Steam for Linux development started in earnest a few months ago. Newell has been outspoken on his disdain for Windows 8. He feels that Microsoft is creating a closed platform akin to Apple. Linux represents an open platform that fits better with his philosophy.