I think I broke my game D: I went into the massive crater's mine dungeon, acquired the master key, but did not complete going through the whole dungeon. When I came back to it at a later time, I did not have the master key for the dungeon anymore, I could not get another key, and the master key gate was locked. This game's a lot of fun though!
Hello! I did have something weird like that happen, now that you mention it. I was in another dungeon, and I noticed that I had a master key already and was able to sequence break the dungeon that way, and the master key in there couldn't be picked up. I didn't think about taking that master key specifically and using it back on the other dungeon I got stuck on. That might let me continue on. Thank you!