Did you advertise your game at all? Did you write to anyone? How did it become so popular?
No advertising, I emailed TouchArcade and PocketGamer a couple of days before release but didn't bother w any other press than that. In the end PocketGamer wrote an article but TouchArcade never bothered.
People keep asking how this happens but there really isn't a magic trick to it. They either gloss over it when I say it or just don't want to hear it, but the goal HAS to be "make a good game". A game that's good enough to get featured by Apple, and then good enough that people keep playing it because they like it. (note: this isn't aimed specifically at you or meant as a complaint, Noroup)