HI! Your game is very fun and challenging. I really liked the concept and the mechanics are interesting too. The only thing, which isn't negative, but leaves me a little in doubt, is the sudden increase in the latest waves. Especially the last one is almost impossible to take down even though all the blocks for the turrets have been occupied. Overall it's a very fun game, but maybe I would lower the speed of the last wave of enemies.
I like it! ;-)