This implementation for the Windows build doesn't work. You can't just load a game from an HTML file on disk. Throws the following error:
"Failed to download file Build/Ratter.data.br. Loading web pages via a file:// URL without a web server is not supported by this browser. Please use a local development web server to host Unity content, or use the Unity Build and Run option."
I can say from experience you're going to have to create a production build of the game from Unity that leaves you with a .exe file to run.