I think the best part about the game is art! (Don't get me wrong, I like the gameplay too)
I think the gameplay was pretty dynamic, by that I mean you get 10 chickens that die really fast and you have to get more chickens again, and I liked it!
Attacking was pretty hard because it was bound on Z and the chicken was attacking the place it stood on.
Also, you should add some background music to the game, because this would add more "life" into the game. Overall I liked the game :)