Hey,
I was trying to dump a copy of "Whac-a-critter" [1] I recently got, and it just dumped the same 8kB over and over, instead of dumping 512kB of data.
Apparently, support for the Realtec mapper is missing in Retrode, though support exists in a number of emulators, including Blastem:
https://www.retrodev.com/repos/blastem/file/tip/realtec.c
If somebody in the US wants to have a copy of the game, I'm happy subsidising buying this auction:
https://www.ebay.com/itm/Funny-World-Balloon-Boy-Complete-Sega-Megadrive/163768864639
Cheers
[1]: https://segaretro.org/Mallet_Legend
Interesting that you brought this up as I'm currently working on a potential Sega MD/GEN firmware update.
I'll pick up a copy and take a look.
Excellent, thanks!
And don't hesitate to let me know in my DMs if I can contribute (monetarily) to the cause :)