It would seem that the Steam platform has a way with self-cleaning its library. I’ve noticed a few times where free-to-play titles would seemingly disappear from my games list as if I had uninstalled them yet their files are still present in the Steam data folders. The straight-forward way to restore the library entries is to reinstall the game – an expensive proposition for those of us trapped under data limits.

After having this happen a couple times myself and not having any luck with the internet for answers, I dug my hands into the issue. Turns out it was pretty simple to restore the installation details in the Steam library.

Note that this -only- works if you still have the game’s data files in your ‘steam\steamapps\’ folder. If those are somehow lost too, then you do have to re-download.

Sample appmanifest File

Here is the step-by-step to fixing this mess:

1. Make sure Steam is completely closed. The fix won’t work if any part of steam is running.
2. Open explorer and navigate to your ‘steam\steamapps\’ folder. You will find files named appmanifest_######.acf – one each for every game that is installed in your library – along with various other data files. The ###### portion will be a three to six number appID corresponding to Steam’s database.
3. Find the file corresponding to the game that has gone missing and open it with a text editor. You can get the appID directly from the Steam store. Open the store page for the game you are trying to restore and look at the address bar which should contain ‘/app/######/’.
4. Make the following changes to the content of the appmanifest file or verify that the information within the file is correct:
   StateFlags -> 4
   BytesDownloaded should be equal to BytesToDownload. Use the larger of the two for both entries.
   UserConfig -> installed -> 1
   UserConfig -> appinstalldir -> [verify this exists and matches the full path for the game folder in steam\steamapps\common\<game>]

And that is it! It’s a pretty simple fix that can save you quite a bit of data download. Save the file and start steam back up. The game should reappear in your library and even remember the category it was saved under.

As for retail copies of games, I have no idea if this fix would work. Presumably it would but I’ve yet to have a paid game disappear. It won’t, however, grant you a license to a game that the active account isn’t entitled to.

As an unrelated tip, it’s good practice to set Steam to not automatically update third-party free-to-play games. Most of these games use their own patcher and Steam will overwrite the game files with an older copy if a desync or file verification occurs.