This includes any .exe or software installed. There are limitations — adding a non-Steam game is essentially adding a shortcut to your Steam library.

This allows you to navigate your computer’s directories to locate the game’s executable file (usually ending in .exe). In my case, I wanted to add Rise of Kingdoms to my Steam library.

If you see Failed to add new Steam library folder message, when changing the installation drive on Steam, here's what you need to do to fix the issue.