Thanks for the useful feedback!
Yeah, I should have made in-game instructions / tutorial...
For the restart when the player dies... initially I was going to make a puzzle platformer, so I implemented the restart button, but then I changed my mind and choose to make a boss fights game. Having the ability to restart whenever I wanted was very usefull for testing, so i leaved it and I didn't think about an auto restart.. oops!
Glad you liked the bullet patterns!