I even did a brand new project, generated a new key for my Game API on the website, nothings fixed.
I've downloaded the file to make sure working on the same file. In a new project, everything works fine. Try following:
- Download the file again.
- Setup a new project and put the files in, you need all three files in the same folder.
- Just enter the game-id and private key into the parameters, leave all other parameters on default value.
- Test game.