Interesting yet simple concept!
(This is mostly a suggestion
) One key thing is the use of event processing to get events to process. I noticed that while typing the above sentence (while game was not the foreground window) that it was still handling the input. Checking if the window is foreground could also solve this.
I noticed one more thing about one door that I unlocked: and that is I could not exit the way I came in for one specific room. The key's name was "key_dungeon1", according to the CLI window.
Also, when you attack an enemy, then immediate leave the room and re-enter, the enemy is still spinning (though the HP seems as if it is reset).
Overall, the game seems to be rather well put together. I really enjoy the simplistic graphics and game style. The background music is also rather relevant (and enjoyable to an extent) and not nearly as repetitive as I have heard in games in the past. The sound effects are also relevant, and not extremely loud.
Would you mind explaining how you set up the area/rooms, items, and entities? I would be interested to hear about this.