I wanted to pass a variable into C2 via the URL to load the page (like youtube.com/?v=###.) I used the method explained here to call doIt(); in my loading screen and extended it using a tiny amount of php. Thankfully, C2 did not complain when I changed index.html and game.html into php files.
This (should be) a working example:
In the example, the code checks to see if a variable was passed. If so, it skips the login screen, silently logs in as the guest/guest user, and then loads the correct node.
I realize this post is old, but if I had found this post while reading the FAQ post it would have saved me some time.