Ravensburger Gravitrax Marble Run ($57.65) Ravensburger is known for its puzzles, and though this is a marble run, it is equally a puzzle set. Even though there are pictograph instructions, it takes careful attention to detail to be able to create them. The set is augmented by an app that has blueprints and also lets you experience the tracks from the marble’s point of view. Many expansion sets are available, but the basic set will keep kids working for quite some time! 8+