I really like the concept of this game. I love tower defense games and the fact that your towers can damage you is really awesome. It's a shame though because the game is almost unplayable.
The character disappears in the first like 10 seconds and then all controls are disabled and I cant do anything. Also might I suggest adding just a simple UI where you can click the tower you want to place? I can see that with more towers you can forget which one costs how much and how to place it down.
Otherwise cool concept, and I like the art too!