Cool game! it gets really impossible by the middle of the game, and the losing condition wasnt very clear to me. I got to about 30% hp left of the boss. I would do some more playtesting to balace the boss, cuz it gets really chaotic, idk how to avoid all that. Maybe reduce the shoot rate of the boss or decrease the bullet's speed.
The visuals are cool too. One background music away from being awesome.