Excellent concept, one of the most solid entry of the jam I would say. The main issue I had with the game was that I often clicked out of the game window when trying to shoot beneath me, so as you can guess resulted each time in my death :d
But outside of that, I would just say that we feel a bit too heavy while jumping, but still this is nothing but quibbling from my part. You did a formidable job, and your game is really good for something made in only three hours!