For the readers reading this that do not know what the Giana Sisters was about, it was basically a Super Mario Bros clone for computers. The Great Giana Sisters as it was officially titled (fans shortened it to simply Giana Sisters) was an almost lawsuit perfect copy of Super Mario Bros, which launched shortly before the female siblings’ game. While Nintendo never officially sued the developers of The Great Giana Sisters, it was rumored, and many will argue till they are blue in the face that it happened and if they could only put the right search terms into Google, they would show you proof. Some enterprising fans have taken it upon themselves to take the levels from the Giana Sisters and implanted them into Super Mario Bros 3.
Okay, the first level is going to seem quite familiar to Super Mario Bros fans, it is nearly a copy of the first level of Nintendo’s original SMB. This similarity within the first level is also the main cuase for concern from fans when the sisters’ game started disappearing from shelves. The play mechanics are the sames as they are in Nintendo’s classic- run to the right, jump on enemies and collect powerups. These similarities also make it easy, and natural feeling, for the levels to be ported into Nintendo’s third Mario adventure.
This hack is available on ROMHacking.net but the actual SMB3 ROM is another story, Nintendo hasn’t released that as freeware or public domain software.