When I was in Japan, I saw this gambling machine where you toss a coin into a pile, and a little mechanical arm pushes the large pile of coins towards a big hol

When I was in Japan, I saw this gambling machine where you toss a coin into a pile, and a little mechanical arm pushes the large pile of coins towards a big hole. Whatever goes into the hole is yours. (I think there is a similar one on iPad at the moment) Once you have tossed your coin, the control is out of your hands. All you can do is sit there and watch the mechanical arm sweep. It is over in about 2-3 seconds. The tension climaxes when the arm gets to its full reach, and it is usually unresolved because the coins end up being herded together into an even bigger pile. (Incidentally, this reminds me of Screwball Comedies http://www.greencine.com/static/primers/screwball.jsp http://www.greencine.com/static/primers/screwball.jsp, where the male and female characters are kept apart right until the last minute). It is the same with Angry Birds. When you launch a projectile, most of the parameters have been set. You may have some control later, but it could not "fix" a bad move. So you now have 2-3 seconds where you are totally helpless, and once it a while, all the stars line up and you get rewarded. Like a monkey throwing a stick at a stationary object. This is insanely addictive. It is a hail-mary gamble that works out often enough to make you keep trying. To earn three stars, one needs at least two "perfect" throws. This is extremely difficult and chancy. The levels have been designed to progressively require smaller tolerance against errors. The Rovio people probably could programmatically control the angle and velocity to see the effects, and from that tweak the pieces to make the gameplay easier or harder.