Cryptokitties is a game that is built in blockchain technology, the process is you will buy cats using Ethereum and breed them so you can earn by selling or trading them and also you will need to install metamask wallet on your pc or laptop to be able to get started. I also heard about it yesterday but I never tried play this game, but it is now trending because while playing you can also earn money, this is also the reason why Ethereum blockchain is congested and now experiencing scaling issues. Here's their official site: https://www.cryptokitties.co/