The game looks great and the theme is very nice in this one. I do have a sore wrist from trying to beat it and I failed... Not sure if the zombies get stronger / faster / spawn more often when progress gets higher but it gets SO hard. Also the melee attack seems quite pointless when compared to the ranged attack. Music and sound would have added a lot to the game too, even if it's just a simple looping background track and some shooting / impact effects :)
Great job overall !