The plot is the same as the original Super Mario Bros., featuring Mario and Luigi (second player only) setting out on a quest to free Princess Toadstool from the evil Bowser and restore the fallen kingdom of the Mushroom People. This game has higher gameplay difficulty than the original Super Mario Bros., with fewer warp zones and power-ups, and more enemies. Six new levels were created for the game, all of which were reused in Super Mario Bros.: The Lost Levels.