Cool aesthetics (isn't this technically a fan game? There is no copyright on the paintings and you can use the image of the paintings for non commercial purposes, but you don't own the IP either)
There is no feedback that let you know that only the skulls can be reflected in the first boss, and the other parts deal too much damage to the player.
The game feels a little stiff. Goya's brush attack range is super small, Would you consider making it a little bigger, maybe like a slash instead of a punch. The character could have better animations, like he was actually painting
Really Cool concept!