Great work on art and general atmosphere.
I'm another WASD enjoyer, so I guess I don't need to say anything about the controls :D But well, game isn't that hard and pretty beatable with the mouse, just a bit more difficult.
I wish there would be more attack patterns for bosses, like some homing projectiles or some bosses could be oriented on melee combat, otherwise some bosses are a bit too similar to others.
P.S. For controls, you can check V-Rising. This one is great example how controls can be, if you are using non-target system to fight, and in some sense it is similar to your game, cuz there many boss fight too in bullet hell-ish style.