Controlls feel sloppy and unresponsive, like you're under water. Also it would be nice if boss's projectiles had some pattern to them, not just random order, because sometimes it feels unfair.
Some sound also would be nice.
But it is cool that you have finished game.

I forgot about wall jump.  But butting mashing worked.

I struggled to find the button to attack first, but after that it became a fun dodge the bullets game. The only thing I have to complain is my hit box, it's too big which make it difficult to dodge. Well, figuring the attack made it easier and after multiple tries I won. Finally!!

The game works on linux as well with wine

You move with A and D and jump with space bar and shoot with enter.

You can wall jump too.