Yume Kōjō: Doki Doki Panic

Yume Kojo: Doki Doki Panic (translated: "Dream Factory: Heart Pounding Panic") is a Japan-only video game developed by Nintendo in cooperation with Fuji Television for the Famicom Disk System. It was later released outside of Japan in an altered format under the name Super Mario Bros. 2. The reason the game was altered into the American Super Mario Bros. 2 is because the Japanese version, released in the US as Super Mario Bros.: The Lost Levels was deemed too difficult. However the American Super Mario Bros. 2 was still released in Japan as Super Mario USA.

Impact on the Super Mario Series
Shigeru Miyamoto was more involved with the development of Doki Doki Panic than he was in the Japanese Super Mario Bros. 2. Many of the game's enemies have become generic Mario enemies, though they were not intended to be that at the time of their creation. This includes Shy Guys, Bob-ombs, Birdos, Pokeys and many more. Of particular note is how Mario, Luigi, Toad, and Princess Toadstool's skills and attacks have been shaped by the skills of the characters they replaced.

Differences Between Games
Several changes were made in order to make the game appropriate for the Super Mario series. Graphical changes were made for certain enemies and characters. Additionally, the albino Mouser boss, perceived as too difficult for American gamers, was replaced with the Clawgrip boss. This change was in tune with the decision to release the edited Doki Doki Panic in place of the Japanese Super Mario Bros. 2, which Nintendo of Japan feared was too advanced for European and American gamers.

Characters (And Their American Counterparts)

 * Imajin – Mario
 * The balanced character, Imajin was the perfect fit for a player just starting out. While Mario replaced him, Imajin's balance in all areas has since become a staple of Mario's in the sports games.
 * Mama – Luigi
 * With the ability to jump higher and lightly hover at the top of her jumps, Mama was a good choice for areas with long gaps. Luigi took her place, and in later games he kept his special jumps.
 * Lina – Princess Toadstool
 * The perfect character for a player with trouble timing jumps, Lina could hover, although she was lackluster in speed and strength. Princess Toadstool replaced her.  Lina's moves inspired two of Peach's moves in Super Smash Bros. Melee and later Super Smash Bros. Brawl.
 * Papa – Toad
 * The most powerful character in the game, Papa could throw enemies and items very far, but he was not very good at running or jumping. While Toad takes his place, in future video games (other than Wario's Woods) Toad was not endowed with the Papa's might.

Miscellaneous

 * The title screen is entirely different.
 * Rather than the storyline taking place in a dream world, it takes place within a storybook. Also, the storyline was about two kids who were reading a book, and ended up getting themselves kidnapped by Wart, which reached his hand from the book and pulled them two in.
 * A save feature is included.
 * The player cannot run by holding the B button, as that's a feature that was exclusive to the Mario series.
 * There was slight music and graphical changes.
 * It takes less hits for Wart to be defeated in Doki Doki Panic than it does in Super Mario Bros. 2.
 * Clawgrip did not exist in Doki Doki Panic. Instead, it was a third albino-colored Mouser.