There is a comment by “tcdev” stating that “I'm currently reverse-engineering Knight Lore”
I think it’s this one: http://retroports.blogspot.com/2016/01/c-implementation-of-knight-lore-complete.html
EDIT: this has a bit of detail on the rendering algorithm: https://retroports.blogspot.com/2016/02/the-fat-lady-hasnt-started-singing-just.html