Amazing presentation, nice take on the boss equipment swapping mechanic, although it lost something for me because the equipment I could pick up before the first fight are the same pieces I got offered after beating the boss.
As others have said, the hitboxes for the boss are a bit hard to work out so it's tricky to know when to dodge and when to attack, and it ran a bit slow (on my extremely budget computer so I can't necessarily count that against the game)
Really though, I can't overstate how strong the presentation is here. The graphics are really impressive and the game's overall look and feel is super cool as well. And the fact you've put in multiplayer is awesome too. Really incredible effort, I hope you continue working on this because the potential is amazing.