Hey, thanks for playing my game!
1) Yes, you are 100% correct, there are tons of bugs and I wasn't able to get around to adding some anticipation/indicators for boss attacks.
2) Also, I was going to add a "tutorial" boss to teach players how to play the game (I hastily wrote some controls in the description).
3) Lastly, I was hastily putting things together last minute to have the bosses appear as you beat them but was out of time.
I found out about this game jam 3 weeks too late (lol) but I do want to complete it!
I appreciate your feedback and will keep these in mind when working on the game.
Thank you! :D