New Super Mario Bros. U is a side-scrolling 2.5D platform game and the fourth and latest installment in the New Super Mario Bros. series. As the sequel to New Super Mario Bros. Wii the game is a follow-up game of New Super Mario Bros. 2. It uses new more detailed background styles and models and introduces the Flying Squirrel power-up acquired by Mario and his friends from an item called the Super Acorn as well as utilizing the Wii U GamePad in Boost Mode. In addition to the core campaign there are also challenge modes.