Bellevue's Valve Software may get credit for the next jump in Mac market share.

The company today announced that it's extending its hugely popular Steam game distribution service to the Mac platform, which has long had relatively few games compared with Windows PCs. Steam and Valve's library, including "Left 4 Dead 2," "Counter-Strike," "Team Fortress 2" and the "Half-LIfe" series, are coming to the Mac in April.

Valve is also going to release future versions of its games on the Mac simultaneous with their release on the PC and Xbox platforms starting in the holiday season with "Portal 2," a sequel to the hit puzzle game initially developed at Redmond's DigiPen Institute of Technology.

"As we transition from entertainment as a product to entertainment as a service, customers and developers need open, high-quality Internet clients," Gabe Newell, Valve president, said in the release. "The Mac is a great platform for entertainment services."

Valve's Steam service will let players switch between Mac and PC versions at no extra charge.

John Cook, director of Steam development, explained further in the release:

"We looked at a variety of methods to get our games onto the Mac and in the end decided to go with native versions rather than emulation. The inclusion of WebKit into Steam, and of OpenGL into Source gives us a lot of flexibility in how we move these technologies forward. We are treating the Mac as a tier-1 platform so all of our future games will release simultaneously on Windows, Mac, and the Xbox 360. Updates for the Mac will be available simultaneously with the Windows updates. Furthermore, Mac and Windows players will be part of the same multiplayer universe, sharing servers, lobbies, and so forth. We fully support a heterogeneous mix of servers and clients. The first Mac Steam client will be the new generation currently in beta testing on Windows."