This is pretty fun and music is a banger. I love the implementation of bullets having another effect if you shoot it at yourself or shoot it to the enemy. I also love the different phases of the boss, how it evolves based on the roulette and it's never exactly the same in two different runs.
I think if you decide to expand this game after the jam, I'd suggest introducing to the player the different bullets more slowly instead of all of them all at once, I felt quite overwhelmed and kept checking the bullet guide but that might be because I have the memory of a goldfish at times, and adding some more SFXs, it was very hard to tell when I got hit from the boss' attacks.