The player takes on the role as the secretary of Sherlock Holmes, and while he is away on a case, the secretary answers a phone call asking Sherlock to solve another case. With the detective away, the secretary decides to solve the case instead. On the island of Nursree, the nursery school kids are causing a riot because the nursery rhymes are wrong. To remedy this situation the player has to meet nursery rhyme characters and make the rhymes true. For example Humpty Dumpty can fall without breaking, so the player will need to break him. The Case of the Mixed-Up Shymer is a text only adventure with a description on the screen of the surroundings and the player types in commands to solve the case.