https://mailchi.mp/92f0d4128f13/project-gt
If you're running your application from the executable or debugger directly then you must have a steam_appid.txt in your game directory next to the executable, with your app ID in it and nothing else. Steam will look for this file in the current working directory. If you are running your executable from a different directory you may need to relocate the steam_appid.txt file.