One recent version I “uncovered” was included on a cover mounted floppy disk on MSX-FAN magazine from 1994/06. This is a free game created by a reader and distributed through the magazine. Old school.
The MSX community is very helpful and open, because it has ties to the West - the platform was fairly successful in Europe. So it was easy to find an archived scan of the magazine, and an image of the floppy disk elsewhere.
I then set about using the fMSX emulator to install the game to a blank floppy disk. And to a ROM just for kicks. At this point I hit a roadblock because the fMSX emulator wouldn’t play the game, though other emulators would, but fMSX is the only emulator that works on 3DS and playing on there was my goal. So, whilst looking into the source code for the emulator, I figured out there was a bug with the default settings for specific models of MSX. So I fixed the bug, submitted my changes to benefit other RetroArch users, and was finally able to play the game!
It’s an interesting version as it adds a shop between rounds from which you can buy special “trick” cards using the points give earned in the game. It is unique in that regard, and it was a pleasure to uncover it and play it. I doubt many people have played that game since the 1994!