Good game, but i think the weapon is a bit overpowered. You dosen't know what is your game purpose and magically after 3rd wave you win xD. And after all I really got a lot of pleasure after playing this. My thoughts that you need to balance weapons and the game needs some story, because you as a player really dosen't know why you need to kill these zombies.
The concept of the game unusual, I'ts a good merge of strategy and tower defence genres.
So in my opinion developers have a lot of perspectives in future! Good luck, guys!
p.s. After a couple of waves game starts freezing a bit, but its dosen't lagging while you playing.
9/10 my conclusion