The game was really fun — the simple job of smashing rats with a hammer worked really well! I liked the aesthetics they fit the vibe perfectly, although it was maybe a little too dark at times. The music and sound effects were great, especially the little 'ow' the rats make.
I did run into a possible bug: I think the map generation might not be properly removing the previous map, because by the 4th floor, there was a lot of strange clipping happening. After I killed who I assume was the 'Rat King' (unless you play as the Rat King?), the floor glitched out and I couldn’t progress through the trapdoor.
Also, if you could enable the Fullscreen button in the Frame options, that would help — right now, if you exit Fullscreen after launching, you can’t get it back without restarting.
Overall, though, I had a really good time with it!