This is a very cool and enjoyable game. I'd be really interested in knowing what framework/library was used to make it. I inspected the source and can see the game is done on canvas, but can't work out more than that.
This is incredible and just what I wanted. Chrome extension and mobile app, and I could even seamlessly import all my pocket data direct from pocket. Absolutely using this. I don't tend to read things offline as much since internet is everywhere now, but I love having all my bookmarks in a nice browsable format with tagging.