This is just a pet peeve of mine. I don't understand why you ask "Are you sure you want to leave this page" when I click back, or try to close the tab. I am sure - that's why I tried to leave.
Actually, it's a Backbone.js application. It uses the browserify library to load other modules, which is what the "require('blah')" bits are. this confused me too when I first read it. so essentially you can run this on a static file server like GH pages.
As far as I remember in order to get the GitHub authentication piece working you need to use an external app simply for the authentication with GitHub. DevelopmentSeed also wrote an app for this called gatekeeper (I think) which I believe is a node.js application.
I've noticed a strange bug with the latest version of Chrome where pages sometimes don't render. Try opening the developer tools, this usually causes the page to render for me.
I can't recommend Angular.js enough. I've been working with it for the past few months and find it to be really enjoyable. The docs aren't great (though getting better), but I found these tutorials pretty good for getting up and running: http://egghead.io
edit: fixed typo