No checkpoints? Have to start from the beginning? The combo system is crap, the bats are too powerful and too hard to beat, and the damage they do is ridiculous. The idea that you can't progress if you don't kill ALL of the zombies is not good, it would be better if you get the percentage of how many you have to kill, or sth. The graphics are good, the movement is sloppy. Played it on easy mode, died in level 2, so yeah, I don't want to try it on harder modes.
It's not a bad game, it's just that it needs a lot a lot of polish. Hopefully, you'll improve it later