Played through it; great job!
The sound effect from hitting mobs was very satisfying. However, they seemed to have invincibility frames after getting hit, which didn't match up with the visual flash. Maybe time the flash to indicate the damage window?
If possible, maybe only have mobs respawn if you move at least two screens away from them, instead of as soon as you leave the screen.
Did you do the sprites and music yourself? Very well done, especially the dungeon music.