This is a very popular ethereum game (quite adorable too) that consists of feeding and collecting kittens that can then be sold at different prices, depending on the level they are at. It was one of the first of its kind and has millions of satisfied customers worldwide. After its launch in 2017, games with the same idea of collectable tokens began to come onto the market.
Kittens can only be bought or sold with cryptocurrencies and their operations are fully traceable as if you were doing a normal crypto exchange. Currently, many mobile games similar to this one have been released, with the main objective of feeding kittens or puppies and then selling them at a higher price. It is a game that at the beginning had a lot of acceptance, but currently it has not had much progress.