Super Mario Bros. 2, known as Super Mario USA in Japanese, is the second game in the Super Mario series outside Japan. This release of Super Mario Bros. 2 is completely different from its original Japanese counterpart, known as Super Mario Bros.: The Lost Levels. Being in fact a version of Yume Kōjō: Dokidoki Panic with a different storyline and protagonists swapped for Mario and his friends, one of the central game mechanics that differentiates Super Mario Bros. 2 from other Super Mario games is that players can select four characters (Mario, Luigi, Toad, or Princess Toadstool) and each of these characters have their unique gameplay mechanics, offering advantages and disadvantages in their stats. Another distinction is that players cannot defeat enemies by stomping on them, they need to either toss items at enemies or pick up and toss enemies at each other to defeat them.