What games on MSX use "save games", and how does it look? Would be nice if there were some screenshots and/or videos from it. I'm thinking of this kind:
and not the "type-in-password-kind".
Let me know if there are any products you think has handled this very well - or even the opposite, if there are variants that do not meet your expectations.
IMHO the best is to have multiple save options in a game.
One of the most standard ways for MSX is saving to disk or FM(PAC). Most Microcabin games use both of them. You can also add save to Panasonic Turbo-R built-in SRAM.
Another popular way to save is to cartridge FLASH memory since most new cartridges are FLASH-based. Examples would be Manbow 2 or DEVA. In this case, if you take cartridge with you and continue playing on another MSX, the save will travel with you too 
Some nice pointers here already! Great! Thanks Grauw and max_iwamoto.
Another popular way to save is to cartridge FLASH memory since most new cartridges are FLASH-based.
What I had in mind.
Examples would be Manbow 2 or DEVA.
I found that Manbow2 is not sold anymore, but I could test the functionality on file-hunter.com DEVA - not sure where I can get it.
Some nice pointers here already! Great! Thanks Grauw and max_iwamoto.
Another popular way to save is to cartridge FLASH memory since most new cartridges are FLASH-based.
What I had in mind.
Examples would be Manbow 2 or DEVA.
I found that Manbow2 is not sold anymore, but I could test the functionality on file-hunter.com DEVA - not sure where I can get it.
DEVA is sold out AFAIK. But there is another game you can check...
You can look for source/ROM from this post. It will have all code that you need:
https://msx.org/forum/msx-talk/development/i-have-finished-it?page=0
