My wife shot me a link to this article:

Why Angry Birds is so successful and popular: a cognitive teardown of the user experience

Recently clients have asked about the phenomenally successful casual computer game Angry Birds, designed for mobile phones, tablets and other platforms…. Why is this seemly simple game so massively compelling? Creating truly engaging software experiences is far more complex than one might assume, even in the simplest of computer games. Here is some of the cognitive science behind why Angry Birds is a truly winning user experience.