I've searched for it before, but couldn't find anything. M58846 official documentation is sparse as well, as I said on IRC I had to guess some of the opcodes.

I got an interesting link from MetalliC yesterday =)

It's a 80s USSR clone of Nintendo G&W Egg. The MCU is a КБ1013ВК1-2, probably a clone of a Sharp MCU. There's a 2KB ROM in the .exe resources, the data looks similar to Sharp MCU code.