Super Mario Bros. Wonder has some of the greatest Super Mario courses ever created, with many of them relying on music, sound, and color to convey their mechanics. The courses range in difficulty from being fairly simple to being more challenging than any in recent memory, aside from perhaps the courses made by players in Super Mario Maker. Each world in Super Mario Bros. Wonder has a secret entrance to Special World — an extra world with the most difficult courses in the game, all based on Wonder's standard worlds.
Source：https://www.cbr.com/super-mario-bros-wonder-special-world-course-guide/
