That was fun! You kept your scope small (or "classic") and just polished what you had really well. The pixel art is cute, I especially enjoy the bounciness of the slime enemies. Movement feels good, especially once you get some upgrades. Combat is simple, but getting freedom over what stats to upgrade keeps it engaging throughout the game. Most of the critiques I have are rather nitpicky, but here they are anyway: I wish enemies dropped their gold sooner so I didn't have to wait for their death animation to finish, some enemies are a bit too close to screen transitions so I bumped into them when going between zones, and I wish there was a clearer "point of no return" before the final boss, because I finished the game with 40/41 rooms seen, and I never got to back to explore that 1 room.
Oh yeah, and the ending made me laugh out loud.
Very solid job!