This is awesome! Great work! I love playing around with these older game engines that have source available, its really neat to explore how they work, and fiddle around with it.

If you haven’t already, Fabien’s write ups of the various ID engines are a joy to read: https://fabiensanglard.net/quake3/index.php

Shameless plug: I also like to play around with old game engines: https://github.com/bishopdynamics/Continuum