I'm pretty sure most of us had a Gameboy console at some time. I still do, in fact. One of the interesting things aboug my Gameboy (Advanced SP) is that I own a game card called "128-in-1". It's just as the name said: there are 128 games on this cartridge. Mine contains Super Mario 3, 4 and 5, Mario Kart Super Cirquit and a few smaller and bigger games I've forgotten about. There was just one teensy-tiny little problem with this cartridge: saving your game didn't work. Every time I booted my Gameboy up again, the save data was no longer there and I had to start all over again. I was five back when I used it the most though, so I didn't really mind, lol. Do/did you also have one of those multiple-games-in-1 game card for your Gameboy? Did those have the same issue as mine or not?
I'm not surprised that your saves don't work, those multicarts are bootlegs and exist for various systems, but I'm mostly familiar with NES ones. I know the Famicom in particular has tons of them but its international counterpart has a few as well. Some multicarts like that may be official in Japan or something, I'm not a total expert on it so correct me if I'm wrong and you know better, but I believe that they're all bootlegs and at least know for sure that the vast majority are. You also find the exact same thing going on in weird cheapo bootleg plug-and-play systems, only they take it to ridiculous extremes like having thousands of the same game over and over again under different names and other nonsense like that. I didn't own one, but this girl who lived across the street from me growing up had an NES one (or rather her older brother did) and we would play it all the time. I believe that particular one was called "51 in 1" and just had bootleg copies of 51 NES games, but often with messed up names and of course no saves (though being the NES it was not uncommon for games to not have a save feature as we know it today to begin with so it's kind of a non-issue there). The example I remember most (and which we played the most) was the original Mario Brothers game (the 1983 arcade one, not the famous platformer although that was there too of course), but on this cartridge it was called "Mr. Mary". No joke. The game was otherwise the same except for the weird ass name and title screen. I have fond memories of that old bootleg multicart.
