When the Super Famicom
to those of us outside of Japan
) was linked up to the Satellaview
online service one of the types of games that Nintendo
offered was online serial versions of some of their classic titles such as, in this case, Super Mario Brothers 2
(known as Super Mario USA
in Japan). Every week a new level of the game was available for play in its Super Mario All-Stars
incarnation, albeit with a few tweaks and changes.
One of the largest changes to the game is that Mario is the only playable character; Luigi, Toad, and Princess Toadstool sit this game out. Furthermore, much like how Super Mario Advance would later challenge players to find hidden Yoshi eggs in Subspace, this version of the game includes hidden golden Mario statues that must be found. There are three hiding out in every level, and collecting one gives up a 1-up and a life meter refill. The game also keeps a running score (a first for this game in any rendition) and pressing Select will reveal the "Today's Results" screen that lists the top scores and so forth for the day. Furthermore, the classic music has been removed entirely as the game was supposed to be played while a radio talk show broadcast was going on. The music would have overlapped against the speech, so it was struck.
Seeing as how only one world was available each week, the hidden warp zones have been overhauled. Instead of warping players ahead, the warps take Mario to a mini-battle with Wart, the game's main villain. Defeating him earns Mario a 1-up and returns him to the Stage Select screen. A ticking timer in the corner of the screen counts down the fifty minutes the game was available per day and at certain points on the countdown random events would happen, such as Birdo attacks, sudden invincibility, player swaps (this provided the only chance to play as someone other than Mario), and other sudden changes.
The game, being a part of a defunct online service, is long gone, but the ROMs of several worlds have been spotted in the wild. However if it's a Super Mario Bros. 2 fix you're looking for, there are plenty of other more easily available ways to get it.