Basically what the title says.

I want to do this, because I want to copy my Mac game to my Windows PC, without re-downloading it.

  • You could try a backup and restore; worst thing that happens is that it won't let you restore.
    – Nick T
    Commented Oct 17, 2011 at 21:06
  • 3
    The windows version has .exe files inside it, and .dll's, which are not compatible with Mac. Commented Oct 17, 2011 at 21:17
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    You can restore from the Windows backup on a Mac - it doesn't need the exe to restore, it searches for the other binary files in the directory. I just did this now on my PC. Commented Nov 1, 2011 at 16:24

1 Answer 1


The executables and libraries may be different between Mac and Windows, but I would expect the assets to be the same in most cases. And the assets are what take up the most space.

I would copy the files over and then open Steam, go to the Library, right-click on the game and hit Properties, go to the Local files tab, and hit "Verify integrity of game cache". That should verify the assets and allow you to download the platform-specific files.

I've only done this Windows -> Windows with partial backups of games, but hopefully this works! Edit: David Freitas confirms in a comment on the question that you can actually do a regular Steam backup and restore without copying files manually, awesome.

  • The files should be the same, but the arrangement might be different. For example, a proper Mac game would move all the assets into MyGame.app/Contents/Resources/ instead of the usual Windows practice of leaving them lying around the application directory.
    – CyberSkull
    Commented Oct 17, 2011 at 22:47
  • @CyberSkull Yes, I'm hoping Valve has forgone that. If I had a Mac I'd experiment with it. Maybe there's an easy mapping between them if it's not exactly the same. Commented Oct 17, 2011 at 23:01
  • I can't really comment on the probability of success because I don't know if the game is packed into a bundle or not and I don't know the extent that Steam's verifier can map the files. But it's also up to the developer on how they want to arrange the files outside of the minimum constraints of the OS.
    – CyberSkull
    Commented Oct 17, 2011 at 23:14
  • @CyberSkull it still cannot read DLL's and .exe's, so its irrelevant on organization, since hl2.exe can't even be launched. Commented Oct 18, 2011 at 0:34
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    @SimonSheehan What we're trying to get at is if the file organization is similar enough, you don't need to re-download all of the assets (the bulk of any game), but just the executables. It's the difference of 10 minutes for the few megabytes of the executables versus hours for the gigabytes of the whole game.
    – CyberSkull
    Commented Oct 18, 2011 at 2:19

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