CryptoKitties

CryptoKitties is a blockchain computer game on Ethereum developed by Canadian[1] studio Dapper Labs that allows players to purchase, collect, breed and sell virtual cats.[2][3] It is one of the earliest attempts to deploy blockchain technology for recreation and leisure.[4] The game's popularity in December 2017 congested the Ethereum network, causing it to reach an all-time high in the number of transactions and slowing it down significantly. https://en.wikipedia.org/wiki/CryptoKitties