Written in plain readable C, open source, iconic game. Same with doom. This is also from an era where there wasn't that much abstraction and "software renderin

Written in plain readable C, open source, iconic game. Same with doom. This is also from an era where there wasn't that much abstraction and "software rendering" was the norm so the implementations tended to be much more straightforward, this makes it so that worst case scenario, you just write to whatever the equivalent of a framebuffer is in the target implementation.