The art of the main character and environment looks really nice!
My biggest issue with the visuals is the low contrast between the rats and the black-and-white tiled floor. Most of my deaths occurred there, as it was challenging to distinguish the rats from the tiles. I believe that having an indicator for the last remaining rats would be helpful; I spent a significant amount of time searching for them.
I think the game has a strong foundation, and it would be fantastic to see it expanded upon, especially with the addition of newer enemies and weapons!