@Moon @denza252 it was pretty simple. each animal has a set of body parts and would assign a random one to the chao when fed, plus some set stat growth. the colored rods would improve one stat. doing activities (boxing, racing) would use these stats.
good/evil would be based on which character treats them nice/poorly. there were some scripted evolutions based on some requirements which made it feel more dynamic than it really was. as much as ppl wanted it to be a standalone big game it was really very simple and just a side mode you check in on every once in a while.