I dont know where to post this, but this will be interesting from a developer from Blue Fang Games about zoo games, hw they changed since Zoo Tycoon 1 to Planet Zoo in these 20 years.
https://egmnow.com/the-evolution-of-animal-conservation-in-games-from-zoo-tycoon-to-planet-zoo/
Interesting he mentions Zoo Tycoon 3 was in the works but was ditched in favor of mobile/social games. Some of the concepts in the cancelled Zoo Tycoon 3 were used in Planet Zoo.