After a series of, well, less than subtle hints last week developer Valve has confirmed that it will be bringing its’ previously Windows based online distribution system – Steam, to the Mac platform.

Last week Valve released a number of promotional images to the media prompting a big announcement from the company. The nature of the images all but confirmed that Valve titles will soon be made available on the Mac platform.

One of these featured the silhouette of a Team Fortress character set on a lime green background – suspiciously similar to iPod advertising of yore. Another featured Half Life protagonist Gordon Freeman clad in white armour holding a crowbar – the crowbar just covers a logo that resembles an Apple.

In April a library of games including Left 4 Dead 2, Team Fortress 2, Counterstrike and Portal will be available on Mac. In the future Valve will release titles simultaneously for Windows and Mac.

“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,” said Valve’s John Cook, who-according to Shack News, explained the following:

“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.”

“Checking in code produces a PC build and Mac build at the same time, automatically, so the two platforms are perfectly in lock-step,” added Portal 2 lead Josh Weier. “We’re always playing a native version on the Mac right alongside the PC. This makes it very easy for us and for anyone using Source to do game development for the Mac.”