CryptoKitties

CryptoKitties was the first decentralized, open-source game to popularize NFTs, built on the Ethereum blockchain by Dapper Labs in 2017.

Although it had a slow start to adoption, it quickly gained momentum during the NFT hype cycle and has attracted over 1.5 million users.

Players can collect, breed, buy, and sell cats that vary in rarity and appearance.

Each cat is an NFT, enabling players to profit from in-game activity or through NFT marketplaces.