My gaming PC (which runs on Windows) has very limited bandwith: I can connect to the internet, but cannot download a game. However I do have a macbook with access to a network with unlimited bandwith. Is there any way I can download Steam games (for Windows) on my mac and then transfer them to the Windows PC?
Most multi-platform games share a large amount of data between platforms, even though the actual executable is different.
Let's look at Half-Life 2 and other Source games. They have lots of
It also works the other way around: copying files from Windows to Mac.
What I've described should also work on most steamplay titles, that are available on Steam for Mac and Windows. (but you might need to copy files from subdirectories inside
However, if you want to download a Windows-only game, then you might need to run the Windows version of Steam. You may achieve that using one of the many virtualization options (VMware, VirtualBox, Parallels), or even try your luck running Steam under Wine (but that might be too buggy).
I'm not sure, but you might be able to do a back up of the games on the Mac and then transfer them to the PC. Obviously the executables are different between the Mac and PC, so I'm hesitant to suggest this. The sure fire way would be to use boot camp or parallels on the Mac to download the Windows versions, then back everything up (in the menu, Steam->Backup and Restore Games...) and transfer them via external harddrive.