I liked the game, solid graphics, easy controlls and a simple to understand.
But hard to master, the lack of feedback when the enemies will shoot (even when they shoot in periodic spaces) makes it almost unpredictable if you get/got hit, particularly when you are close to the player (you need to get close).
I think with a bit of feedback before the enemy shoots (be it a color change of the enemy or something), sounds and a way to maybe dodge the bullets now and then, this would be a great game with much potential to grow!
I am thinking of levels, more enemy types, maybe a story (of course not in the time of the Jam but maybe later)