13KiB is such a constraining limit, and extra funny considering modern events.

Hobbyist: I've deleted faces to use less bytes.

Console maker: We're discontinuing discs. Worried about games being over 100GiB? Screw you, get faster internet.

EDIT: Also not exactly sure how they did the models. I could see precision being a grid/editor/export setting (or obj parser/optimizer?), though maybe they wrote them by hand or did it in Trenchbroom and thus handled by their own map loader. Controlling precision through scale too, maybe?