I made a bunch of changes to this build, mostly in the way the code is structured to be a lot more object-oriented. But I did add a few new features.
There can be multiple monsters. Monsters spawn randomly and now move around the maze. If you beat a monster in combat, it dies and doesn't come back.
There are potions that randomly spawn. You can pick them up, and to use them you press A on the map to restore 1 HP.
There's a new game over screen, adapted from Skull-A-Day: skulladay.blogspot.com/2007/06/16-8-x-8-skull.html.