https://www.eurogamer.net/death-from-ab ... p-fight-md
The cover the article references but for some reason doesn't include:

A couple of choice quotes from the interview:
it was about two weeks later that I stumbled completely by chance upon the Toaplan office in the second floor of a supermarket building!
While I was in the middle of developing Bare Knuckle 2 in the fall of 1992, I was told I didn't have much longer to live. I had been incredibly busy from spring of that year, concurrently developing 4 games including Slap Fight MD. I was over working. The disease greatly affected the development of Slap Fight MD. By winter of 1992 I could not go to the office. I had to take my work PC home and direct development from there. By spring of 1993 I could no longer leave my bed. I was just waiting for death.
The game a man defeated death itself to complete.Toaplan gave us a lot of reference materials to help us with the development, but the graphic data for the arcade Slap Fight was originally made on an SMC-777 computer. This computer was top of the line for its day, capable of displaying 4096 colours. All the graphics data was stored on double density floppy disks, and made using Toaplan's own in-house software tools (unfortunately, they didn't give us any documentation for the data format this software used).
All the sprite editing and graphic work was done on the SMC-777. Toaplan's software tool could only create 8x8 sprites, so Toaplan had to draw and plot out the stage maps on graph paper, doing everything by hand, and using as few 8x8 sprites as possible. I was amazed when I learned that Slap Fight, which was known for its high quality graphics at the time, was made this way.
Material about the actual dev systems always fascinates me, because of how arcane it is, what it reveals about the circumstances around a game's creation, and especially because it's almost always excised as "the readers won't care about that" kind of stuff. Sony's SMC-777 was actually designed to be an accessible Z-80 based 64k RAM home computer, albeit one with an upper mid-level price. To be usable by people who didn't understand computers it didn't even require command prompts; its filer offered a cursor based menu, which was something back in 1983/84.