It works!

This is the current build.

There are still some things on my todo list, such as GPU/CPU temp monitoring, loading a whitelist of fullscreen apps to ignore, and some other stuff I can't think of.

I've included some batch files to easily install the service. I forgot to add an uninstall batch file. If you want to uninstall the service, use "IdleService.exe uninstall" in an elevated command prompt. See the example batch files for more information.