Yea but, the thing about ethereum is its conceptually about building on top of the technology.
There is nothing stopping people from building on top of even the cryptocat system, making a game where these cats are usable for any of your listed game mechanics.
It doesn't need any kind of api-integration to cryptocats, it just needs to reference the already public cat compendium.
Wow this is an idea that I hadn't even considered before! That any smart contract is just a little piece of code with an API and an Ether cost. I'm getting so many ideas for cryptokitty horse racing...
There is nothing stopping people from building on top of even the cryptocat system, making a game where these cats are usable for any of your listed game mechanics.
It doesn't need any kind of api-integration to cryptocats, it just needs to reference the already public cat compendium.