For the open source category, you'll need to have a README file and License file.
Music is catchy and very fitting. I would have a "Press B to start the game" on the first screen as this isn't an intuitive way to start playing. It'd be great if you had an animation for the attack, rather than just seeing the enemy health bar depreciate. Do we have health in this game? How do we tell?
Great job on this game and interesting take on the theme.