Those files have been created for smartjeux to make html5 games with fixed size full screen ready even they are not.
It’s basically uses zoom to make games bigger for bigger screen.
Replace gamewidth and gameheight with the default game size. Replace src with the html5 game url.
You don’t need to get access to the game source code.
Its works on every web browser.
You can try with the game called Mahjong Chain.