It was fun but definitely needs changes
First of all, the enemies shouldn't be able to shoot you through a wall.
Also the bullets shouldn't have that limit that makes the first bullet shot restart its path if you shoot more than nine times or whatever.
I personnaly would have preferred if you had used the wasd keys to make it easier for right handed people. Or better yet, a "set controls" option.
I hope that you take heed to at least a few of my suggestions to make an even better game.