Getting an App Icon right is tricky. You've gotta make sure that it communicates something about the game, but you've also got to make sure that it stands out in a crowd. All in a very limited amount of space.
For us, the one thing that we were 100% sure we weren't going to do was do a yelling guy, a'la Clash of Clans and almost every game under the sun. So we're in the midst of experimenting a bit. Got a favorite? Let us know!