I dunno, I bought it the week it came out and haven't played more than 5 levels... Even with the "retro" update... =o/
I admire the honesty syntheticvoid and I'd like to know why you get bored after 5 levels? Maybe it is not your type of game but every 5 levels a new enemy/concept appears in order to keep the game fresh and challenging. To my knowledge there isn't a game with these types of mechanics on iOS so it would be helpful to find out what about the game doesn't peak your interest so I can tweak it/add to it!
Let me know what you (and everyone!) would like to see more in the game as I will continue to work on it throughout this next semester, including adding gamecenter and more modes of play!