Into replicating rigify

… I want to replicate rigify, what should i expect?

I already learned to replace bones by objects, i rigged eyes, made shape keys with eyelid and mouth… It works, pretty well indeed, without applying the rigify script of course…

Rigify somehow doesn’t generate everything and its inverted kinematics doesn’t apply at all… Seems like it’ll need some rework on it…

But i’d like to replicate the kinekatics for fingers which generates much well in think… And i’ve got a few tutorials about IKs so i’ll about be fine… But i don’t want to miss a thing - what should i expect if i want to replicate it by hand (and have it to be game-compatible of course)