Agreed about some item progression providing a nice incentive to explore. (The procedural generation is a bit too simplistic as well, since you can guess or know the possible layout if you've played enough)
More monsters/boss would also be cool.
I can't take much credit for the graphics as the sprites are from Kenney's 1-bit Pack and recolored using the DawnBringer 32 palette. Kudos to them for making cool stuff and putting it out there for use!