Several months ago, I was looking for a reliable way to calculate the total size of a Workshop collection for my Garry's Mod server, so I created a Lua script using the internal Facepunch Steamworks library but I also wanted to have this way without necessarily going through the server console or starting my game.
So I decided that using the shell (without creating a GUI) and creating a small program to achieve this result would be a good way to learn C# since my knowledge is limited to classes, but it would also give me a quick way to calculate a Workshop collection.
There might be some issues/inconsistencies in the code but of course any report/pull request are welcome!