Wow, very good! The art, sound and level design are great
It was a lot of quality content created in 15 days, congratulations :)
The only thing I believe needs improving is resolving the continue bug that makes it necessary to restart the game. And I'm not sure if it's a bug or it's the end of the game, but when I defeated the second boss he left the screen and the doors didn't open (apparently he was still alive off-screen and shooting)