Yume Koujou: Doki Doki Panic

Super Mario Bros. 2 began as a prototype for a vertically scrolling, two-player, cooperative action game, but later was re-branded into Yume Kōjō: Doki Doki Panic, a Family Computer Disk System game meant to tie-in with Fuji Television's media technology expo, called Yume Kōjō (lit. Dream Factory). The characters, enemies, and themes of the game were meant to reflect the mascots and theme of the festival. After Nintendo of America found the Japanese Super Mario Bros. 2 (later released internationally as Super Mario Bros.: The Lost Levels) to be too difficult and similar to its predecessor, Yume Kōjō: Doki Doki Panic was improved upon and converted back into Super Mario Bros. 2 for release outside of Japan.