Try save the HTML of this site?
Viewing post in Can you create a downloadable demo version
While having your browser open, you can press the "Save" shortcut Ctrl+S to save a loaded website to your device. This does work for static websites, but I am unsure if embedded dynamic interactive elements are included as well in the html script, since that would blow up the file size immensely, thus bloating website loading time to extreme proportions. Instead what likely happens is that the game is accessed dynamically, and just rendered as iFrame.