In case it wasn't clear, his game isn't just a web app that lives on the home screen as a bookmark. It uses the Titanium Appcelerator, which is a thin native wrapper around a Webkit view. The app logic is written in JavaScript, rendering is done using HTML/CSS and/or SVG or so. FWIW, this actually obeys the arbitrary App Store rules: C, Objective-C, C++ and JavaScript (if run in Apple's supplied runtime) are allowed.