Ethereum sustains its position as the 2nd most popular cryptocurrency, behind Bitcoin. In 2017, a game called CryptoKitties was released on… — Ethereum sustains its position as the 2nd most popular cryptocurrency, behind Bitcoin. In 2017, a game called CryptoKitties was released on Ethereum. It is famous for causing the gas fees on Ethereum to skyrocket and created many bottlenecks for the blockchain.