Earlier quoted context omitted.
Check Quaddicted[1] for some singleplayer maps. The most common engine by far is Quakespasm[2] which keeps the original style but fixes bugs, reintroduces some features from the software renderer that were lost in the original OpenGL version (fullbrights, lightmaps that go above 100%, non-power-of-two textures, etc) and removes and raises some hardcoded limits. You probably also want QuakeInjector[3], which is a "qua…
Awesome, thanks for all of this information. It's much appreciated! Of the 3 quakes, which is easiest to dive into mod development?
Also i forgot to link to the Quake Wiki: https://quakewiki.org/