Valve has confirmed its not entirely secret plans to bring Steam to the Mac, and revealed the extent to which the Apple platform now weighs on the studio's thinking.
Steam will launch on Mac in April, and Valve's games - including Counter-Strike, the Half-Life series, Left 4 Dead 2, Portal and Team Fortress 2 will be ready then too.
But Valve will also make its future games available simultaneously on Windows and Mac, starting with Portal 2 this Christmas.
Valve's biz dev director Jason Holtman said the firm had a new feature called "Steam Play", which allows you to buy a game once and then play on either Windows or Mac.
"For example, Steam Play, in combination with the Steam Cloud, allows a gamer playing on their work PC to go home and pick up playing the same game at the same point on their home Mac," he said. "We expect most developers and publishers to take advantage of Steam Play."
Steam dev director John Cook said Valve had decided to reject emulation in favour of producing native versions of games.
"The inclusion of WebKit into Steam, and of OpenGL into Source gives us a lot of flexibility in how we move these technologies forward," he said.
"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."
Valve president Gabe Newell added his support: "As we transition from entertainment as a product to entertainment as a service, customers and developers need open, high-quality Internet clients," he said. "The Mac is a great platform for entertainment services."