I think with a bit more time you could turn this in to a cool sim game!  Like aha_games said this needs a Menu/UI.   Keep it up, good job and thanks for participating in the jam!

The game looks good, it just needs more stuff (menu/UI, gameplay elements)

I recommend the same as Aitor. A start screen is always a great introduction to a game to figure out what is going on. Game needs a bit more to it. I didn't have to press any of the movement keys, just fire the bullets and killed the enemy every time. I like the art style and sounds. I would tune the sounds down a bit so they aren't overwhelming though.

I recommend you to put a start screen.. maybe indicating the controls too. At start i was waiting when I figured that I'm playing.