Hi Grimwolf, I played your game for a bit, and here's what I thought.
I like the Limbo-esque artstyle, I like the angry birds style gameplay, and I like the precision control I can get over the Balista.
On the other side, I felt that there was too much trial & error to learn where the zombies were. Having a way to survey the map would make a huge difference for being able to plan shots, you could also offer things like a visual representation of your last shot (ala Angry Birds) and perhaps your last angle and lbs listed somewhere, so you have a reference for your previous shot when considering your upcoming one.
I also found your instructions screen to be not completely clear, but was fine once I got into the game and started exploring it (I struggled with figuring out where to click at first, but sorted it out quickly enough)
Also, given that this is your first C2 game (I don't know your history in game development) there are lots of us here that are happy to help you with any questions you might have about how to achieve various things you're looking to have in your game :)