This is a emulated steemGG environment which your can use to test those SDK APIs from your game.
Simply input the URL of your games index.html path into the Game URL: input and click "Load game".
Then the SDK request from your game call will be communicating with the 'Left Side'
Call steemGG.setDebugMode(true) at the start to skip the encryption so it's easier to debug
You can load the sample sdk page and inpect the source code for details as well.