WTF? Can't see it from a desktop browser; can't see it on an iPhone unless I "install" it....
Go away.
Go away.
If you change your user agent to iPhone and go to http://mrgan.com/pieguy/ on your browser I assume you could play it on your desktop.
You will need a WebKit-based browser, as it uses CSS transitions, transforms, and animation properties. The game checks the iPhone-specific property "window.navigator.standalone" to see if the game is running full-screen (i.e. it is installed), but you can work around that in the Web Inspector JavaScript console or editing the source to get the game to load. Then you can click to start a new game, however you're left with no control as it uses iPhone-specific JavaScript for swipe controls.