For all its plausible physics, Angry Birds is more stress-relief than puzzle — less a gravitational/collision brain-teaser, and more a cortisol drain.
Wonderful things, these 2D cortisol drains, but not as mentally satisfying as something like Cut the Rope — another iOS (and Android) game, originally written in Objective-C, and enjoyable in great part because of its perfectly smooth obedience to physical laws.