Before anyone tries to flag this as a duplicate, know that I have already seen How can I move an installed game from one Steam library folder to another. This question is in relation to the top comment on the top answer to that question.

I have been manually backing up my less played Steam games to a large SAN device. I do so by simply moving the game folder to the share and then uninstalling the game in Steam. I do this because I can afford the space and don't want to wait for the compression on top of the transfer time.

Up until recently I haven't been so short on space that I have run into this problem, but now it's happening more frequently. As the comment in the linked answer states, you need to have space enough to install the game after you have already copied the contents to the library. This is because Steam will initially check the free space before allowing you to initiate the installation, which will eventually discover all the files there anyways.

I understand this check is there for a reason, and it's a perfectly good check, but I am trying to find away around it, or to trick the installation process.

I have tried initiating the download, pausing right away, copying the files over to the install directory, and resuming. This doesn't work because Steam downloads to a temporary folder before copying to the final install.

I have tried doing the same thing, but overwriting the files in the download folders. Steam just continues downloading and overwriting the already completed files because it doesn't check them first.

Is there a way to reinstall a game from a manual backup, without needing twice the space of the files free on a drive to do so?

1 Answer 1


If you backup/restore all of the correct files (including correct appmanifest_######.acf file), then restarting steam should make it re-check your library and add the installed games.

I tested it myself just now:
1) I moved the game folder (absolute drift, due to small size) (from steamapps\common) and the appmanifest_320140.acf file (from steamapps\) outside of steam folder
2) uninstalled the game from within steam
3) restarted steam to make sure the game stayed uninstalled
4) moved the game files and appmanifest file back into steam library
5) restarted steam and it immediately added the game to the library as ready to play

You can find the game ID (which is the ###### in the appmanifest_######.acf file) by going to the game's store page on steam and checking the URL. It should be http://store.steampowered.com/app/######/ (the ###### being a number representing the game ID). So, for example, the game Absolute Drift has the game ID 320140, therefore I used the manifest file with the name appmanifest_320140.acf enter image description here

  • Where can this appmanifest file be found?
    – Nzall
    Commented Jan 25, 2018 at 8:35
  • It's in the steamapps folder. Will add it to the answer...
    – Elise
    Commented Jan 25, 2018 at 10:07
  • Can you also include instructions for how you find the number of the game? I know you get it from the store page URL, but it would be nice to have for people who find this answer.
    – Logarr
    Commented Jan 25, 2018 at 17:02
  • 1
    That's a good idea, sometimes I take some knowledge for granted :P
    – Elise
    Commented Jan 25, 2018 at 19:18
  • This is brilliant and it works perfectly. Removing the manifest even counts as uninstalling in Steam, so I'm not even gaining a step with this really.
    – Logarr
    Commented Jan 26, 2018 at 1:39

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