Nice entry, visually charming and consistent. Few things from my experience:
1. I like first dungeon puzzle with a column. However when I was playing with a column I moved it to the corner. Then noticed the button for the closed entry. Maybe you could add another column so there's no need to reenter the room?
2. I didn't kill all monsters as some were neutral to me. But then I got the locked door... I finally decided to kill all monsters and eventually got the key, but I think you should not let player be confused like that.
3. The locked room is empty. I don't know - if it's by design or a bug? The music change suggests some boss but I don't know how to summon him.
4. I also got information from the NPC there's a shiny stone to get. Does it drop in the last room?
5. I think you should keep the rooms orientation. Otherwise it's confusing. Sometimes you can fall into enter/exit loop :)
Keep up the good work :)