Nice game, especially for the short amount of time. I really like the art style and sound effects, though some background music would have been good. I also had troubles getting into the game. I needed to press Y on my keyboard (instead of Z) to shoot. It did take me quite a white to understand that you have to shoot your ship as a missile against the start symbol.
I also didn't get further than the first door as the exploding stars were aiming really well and restarting required reloading the page every time, also requiring to redo the tutorial.