what a really nice puzzle game. it got me hooked because of its interesting art and especially the music and the story about ghost. I tried to put the key on the desk/table next to the door, but nothing happened. I read all hints from the signs, but I did not know how to turn myself into a ghost. I also saw a special blue stone, and it turn orange when I touched it, but I can't figure it out what to do with it. how about adding a hint system that we can use a magic book item to help us to automatically unlock one part of current puzzle level; the character will automatically move to unlock a specific part of current puzzle level after using the magic book. by the way, you forgot to upload your cover image. what a great interesting game for others to miss.