So, ah, I have a lot of things to say, so first of all, the enemies come WAY too fast, they spawn right when you get in the game, I guess you wanted a Call of Duty zombie kind of game, but try making a wave system first. Also, the HP bar on the top left doesn't really mean anything, cuz' when it goes down to 0, you can still play the game, and the enemies all go in a line, even when the cam goes up or down, they stay in in a straight line, so try making a movement pattern for them. Overall, I don't think this game is that bad, it just needs fix some problems, I think this game can and will, do very well, maybe some things that need fixing need a different software, but this game has an okay start.
TL;DR: the HP bar doesn't seem to work, the enemies need a movement pattern and a
wave system, oh, and the bullets could use some animation.