Melody of Mystery, the additional package of the 4th game, is an adventure of waking up the students at the Astral Academy, where the prince we saved in the main game is also educated, from their deep sleep because of the mysterious music box. I can say that they did an even better job with the level designs than the main game, but the levels contain many, many puzzles. Of course, although many of them are optional and fun to solve, some can be confusing and tiring. But overall, it was a DLC that I liked very much and was very satisfying in terms of gameplay. If you liked the main game, I definitely recommend you check it out.