Comment by Eisenstein

Good chance it was John Carmack, probably one the top 10 programmers of all time. He basically built the Quake engine himself. There is a pretty decent analysis of it here:

* https://fabiensanglard.net/quakeSource/index.php

I recommend checking it out.

EDIT: i was thinking of the analysis done on Quake 2, which is more about the engine:

* https://fabiensanglard.net/quake2/index.php

while the one about is regarding the multiplayer system, which is still an amazing bit of dev.

Github:

* https://github.com/id-Software/Quake