- It will require Mac OS X 10.5 and an Intel processor, PowerPC will not be supported.
- Source will run natively on OpenGL.
- Source games for Mac will require Mac OS X 10.5.8 or higher (Leopard), or 10.6.3 or higher (Snow Leopard).
- Source games are not supported on the X3100 or 900-series Intel chipsets.
- Buying certain games for PC will include a free license for the Mac platform, and vice versa. This will likely depend on the publisher which will label games as such with the Steam Play icon.
- Mac OS X and Windows users will play on the same servers, join the same lobbies, etc.
Some of these details are not at all surprising, like the minimum software and hardware requirements, but getting confirmation on cross-platform compatibility and releases at no extra cost is certainly nice. Counter-Strike, the Half-Life series, Left 4 Dead, Left 4 Dead 2, Portal, Portal 2, and Team Fortress 2 have all been confirmed for release on Mac OS X, with presumably more games on the way later on.
Valve also confirmed that Apple's operating system will be treated as a tier-1 platform, which means shorter waits for Mac gamers. It will be interesting to see if Valve's Mac OS X push will prompt third-party developers to start looking at the platform more seriously and making more titles available for it.