Impressive as always. Stone Boss fight is really fun and challenging. Love how smooth the player's animations are but sometimes stuff like turning around, jumping and crouching can feel a little "laggy" because of it, increasing the speed of those animations a little could fix it, unless it's inteded to be that way.
Had the same issues others had with the small spikes coming out of the ground, but the fight still felt fair to me.
Great art on the difficulty settings too. I'm afraid I'll miss all the funny placeholders once you replace them.