Disclaimer: I haven't played it, but I read this article.
It looks like a pet breeding game. You "own" cartoon cats - visual representations of distinctive bundles of characteristics contained in a NFT. You generate more NFTs by "breeding" two existing cats (executing the smart contract), which results in random combinations of their characteristics in offspring.
What to do with them? Speculate on their value, same as any NFT.
As a "game" this sounds incredibly unsophisticated compared to normal video games - something that might have passed during the flash era of gaming, or maybe today on itch.io as a weekend project. The only "hook" outside of this is the speculation / potential to earn (and I imagine if you're in on the scam, earning is a lot of fun).
You basically don't do anything except watch what weird mutations come out from the breeding. In Clusterduck, you can only have up to 30 ducks, so once you hit the limit, you have to throw a duck into the pit to sacrifice it. Sometimes when sacrificing a duck, a large monster spawns from the pit, and if you tap it enough times, it'll spawn a duck with a "cursed" trait of some sort.
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).
Sounds like gacha, where folks feverishly "collect" pointless pieces of little plastic. All these things (hoarding, compulsive buying, gambling) go hand-in-hand [0], and ends up emptying pockets and possibly devastating lives.
CK's breeding mechanics are about as complex as Pokemon Gen1's breeding mechanics, and simpler than Gen3. Congratulations on passing the GameBoy bar. Additionally, all of the talk about openness is now out the window since the breeding code is closed source.
Congratulations on also doing limited time events, welcome to the year 2000 of online gaming!
Thanks! Now there's improvement, from "we're not sure just how simplistic those mechanics are" to "well fuck me that's some first year in college simple mechanics".