Breeding is a complex and nuanced game mechanic, which when coupled with the worldwide marketplace unlocks a dizzying rabbit hole. Once you understand the mechanics, you realize just why a Gen 1 Tendertears would be a grail collectible to own.
I called it more of a sandbox than a game, but there are also Fancy Chases, events where a specific limited-time breeding goal is introduced and it's a race to be among the first to achieve this goal and breed a Fancy Kitty.
Not saying it's for everyone, but it's definitely something that thousands of people found and find pretty darn fun (again: if expensive).