Milon's Secret Castle is an action-adventure game developed by Hudson Soft, first released in Japan on November 13, 1986, and later launched in North America in September 1988. The protagonist Milon comes from a planet where people make a living through music, but he cannot understand music. One day, the evil wizard Maharito attacks Milon's village Ishtar, loots the villagers' musical instruments, and imprisons Princess Elsra in Grand Castle. Milon bravely embarks on an adventure, entering the castle full of mazes and traps, defeating monsters, searching for hidden tools, treasures and money, and finally rescuing the princess and the villagers' instruments. In the game, players control Milon to run, jump and shoot bubbles. Each room is filled with enemies and hidden items; bubbles serve as both weapons and can be used to break bricks, revealing hidden shops or items. Its puzzle elements and challenge make it a classic.