To commemorate the launch of Steam on Mac, Valve is offering up a free copy of Portal to anyone that downloads the digital distribution client from now until May 24. This gracious offer also extends to existing Steam users on the Windows side.

“The Mac is a great platform for developers,” said Gabe Newell, president of Valve. He added, “And it’s also great that we now have the ability to connect with Mac gamers via Steam. This is the beginning of a groundswell of games coming out for and fully utilizing the openness and power of the Mac.”

Valve plans to add new offerings to the catalog of Mac-compatible titles on Steam on a weekly basis. Look forward to a new group of games to drop each Wednesday, with each batch poised to highlight a specific area of Steam functionality.

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