I really like the idea of your game! Something like this was one of our initial ideas but we did something else later. The art is very simple but the animations are doing their job and its quite nice actually. I am missing some sounds there and the ballance is a bit off too. After few upgrades I was able to kill almost all enemies within few seconds so then I got not enough gore to get some upgrades. Overall quite nice, very interesting version of tower defense game and I really like the use of theme! Good job :)