How do they make these games? Are they not written by hand? What engine is used?

Question

WebGL

www.quakejs.com/play?set%20fs_game%20cpma&set%20mo...
What engine do you use for development?

Answer 1

https://github.com/inolen/quakejs
sources :)
https://alpha.app.net/robdudley/post/25037232

Answer 2

the usual engine of the third quake is
written for a long time and needs