I think that AB success comes not only from the perfect execution, but also from being able to occupy previously under-served niche: casual iPhone game that can be played in small increments. One game round (successful or not) takes around 30 seconds, after this you have a choice to continue or to stop. If something more important comes up, you stop, if you are still waiting in line, you continue. Then you are drinking coffee and eating croissant, played few round, back to sipping coffee, played few round more.<p>It's easy to start and easy to stop, and you don't feel that you loose something if you <i>have</i> to stop at this particular moment, and this is really import for the casual game on the phone.<p>Look at the Cut the Rope. It copies AB concepts verbatim - short engaging levels, three starts, cute character (and candy! :) It became quite a successful game. I don't think Tiny Wings will hold position 1 in the charts long - it's cute, but game progress becomes very difficult quickly and "start-stop model" is not as good. The main reason it is (most likely) not going to stick to position 1 is that there is no way to add incremental value by adding new levels and thus rekindling interest and pumping the rating (another ingenious thing Rovio invented or borrowed and perfectly executed).