I bought kitties on CryptoKitties when popularity seemed to peak back in December 2017. At the same time Ethereum hit a $1000 and Bitcoin shot up to $20,000. So I did what any sane person would do and transferred 1 ETH to buy and sell digital cats. It was interesting because this digital economy reminded me a lot of games like Travian that have in game economies, or an even more relevant site would be Neopets which has items you can buy and sell using points you earn from playing games. It’s actually where I got interested in HTML as I learned how to customize the look of my shop.