It is embarrassing but I really only learned more than a decade later that Giana Sisters was not the original.
In Germany, and I guess in many other European countries, Giana Sisters on C64 was really the Jump and Run game (that's what we called that kind of game back then) of the 8-bit era. Super Mario was not heard of. This all changed when the Game Boy came out because it had Super Mario, but this was of course a few years after the 8-bit home computer wave peaked here.
So many of my generation learned about Super Mario years after they knew Giana Sisters.
For those that have never heard about Giana Sisters. It is essentially a Super Mario clone with Mario and Luigi replaced by two girls - Giana and Maria. The levels and the game-play are not 100% identical by very similar.
It was sold only for a very short period of time because Nintendo intervened. It was still hugely popular and most copies were just pirated.
Some company later released Great Giana Sisters games for the Nintendo DS (and presumably some other platforms, maybe PC) with updated graphics. Roughly the same gameplay but very different look and feel.
