Very neat concept, though fighting the boss feels somewhat tedious. I lost almost half of my HP due to swords spawning on top of my face (instead of only spawning them inside the arena add another constraint where it's some not too significant range around the player, so that you can't ever be sniped, that feels unfair), and there also waves of only white swords, i.e. waiting out (maybe a little minRange variable so that it always spawns at least one colored projectile).
Otherwise, super dope stuff!