Also known as Yume Koujou: Doki Doki Panic, this game was originally actually supposed to be a Mario game in Japan, but it got changed to a game about an Arabian family going inside a book. This later became Super Mario Bros. 2, for the U.S. The reason this become Mario 2 was because Nintendo thought that the game made for Japan was way too hard (you can't really blame them), even though it did introduce a few mechanics that are used in some Mario games today. The U.S. version of the game actually did see a release in Japan, known as Super Mario USA.

Also, the U.S. version did use some characters which became standard in some Mario games (just look at Birdo, and the ability to play as Toad).
According to tcrf, Doki Doki Panic was originally created as an advertisement for a "Dream Factory" in Japan (That is what Yume Koujou translates into).

Got the covid-19 vaccine

1. an interesting japanese computer game where two fat guys and a goth chick battle evil monsters by chucking vegetables at them...the game was later repackaged as super mario brothers 2 in the USA

2. a narcissistic. yet incredibly insecure creature from the depths of birmingham uk, incredibly opinionated on the subject of creative form, doki is often seen snipering the successful contestants from the karaoke based "fame academy" shows, we say good luck doki!

The biggest ripoff of Super Mario Bros 2.