Bought the book "The Art of Game Design":
<img src="http://ecx.images-amazon.com/images/I/41xdolUvXzL._BO2,204,203,200_PIsitb-sticker-arrow-click,TopRight,35,-76_AA300_SH20_OU01_.jpg" border="0">
Has anyone else read it? I bought it because the reviews were so positive, and I'm a little way in and it's REALLY REALLY good! Highly recommend it.
It takes some abstract concepts, like "how to make the game interesting" and approaches it in an easy to read and scientific method.