Could you make a guide on how to use the tool?

[sylvester-roos]

For example, my Steam games are not showing up. I thought that adding the root of the game folder would cause it to show up, but nothing happened after I added it.

P.S
Is this the correct place to put this question? I'm not sure what you mean with the 'Projects' category

[DatL4g]

Yes discussion is fine for that, an issue would be okay as well.
GitHub recently removed the "real" Projects feature, so I keep track of adding new features like this.

Steam games are different compared to "normal" games.
DXVK caches from steam games are stored in a separate folder, so I have to read a config file for each game to find it's caches.

You can add the shader cache folder and connect it manually with a repo item.
Shader caches are stored under ~/.steam/steam/steamapps/shadercache or ~/.var/com.valvesoftware.Steam/.steam/steam/steamapps/shadercache

[sylvester-roos]

I've tried a couple of different things but I can't get it to work. These seem to be the logical steps to me:

1. Click the + which opens the 'select game folder' picker
2. Select the shader cache folder per your comment (1172470 is Apex Legends)
   
3. I expect the game to show up, but nothing happens

Where am I going wrong?

[DatL4g]

You did it correctly, but there was a bug with manually added games.

Fixed in the latest release v0.3.1-beta02