This game has got pretty good audiovisual presentation. The Haunting Melody theme is only apparent during the final part of the game, would be better if you could faintly hear that song in the background during some moments of the game before you find the underground tunnels.
The volume of the song told you how close the monster in the maze is so that you can avoid it. And if the monster is near enough for you to see it it's basically game over already, so that Phantom Threat bonus challenge is implemented in an interesting way. Have to say, it's hard to get through the maze, so very unlikely for a player to manage to do so on their first try.
One thing that would be a notable improvement for this game would be to have a "checkpoint" in the underground room from which you have to escape through the maze, so that you don't have to replay the game all over again if you get caught by the monster. Otherwise, good job!