Great work. Bold dive into the 1-bit color palette, clever use of backface culling to hide some walls without much hassle. All the textures and sprites are really crispy and read well.
I was missing some more feedback - explosion/hit particle systems, aiming line, camera shake, monster calls, things like that.
Game could also use some ambient sounds for the dungeon, it feels dead when music isn't playing.
It's cool that you've managed to include a progression system with a simple economy in that small of a timeframe. Well done!