Interactive ePubs

Impressive demo of what you can do with HTML5, CSS3 and Javascript in ePub ebooks by Walrus:

Walrus Epub Demo#3 – Kadath from Walrus Books on Vimeo.

I have to wonder though if they really think that punishing people for reading more by making it harder to read the text is a rewarding game mechanic for interactive ebooks. I personally very much doubt this…