A Non-fungible Token (NFT) is a unique and non-interchangeable unit of data stored on a digital ledger that is blockchain and can be traded. NFTs can be associated with digital files such as photos, videos, in-game items and audio.
First known NFT game CryptoKitties was launched in 2017 on Ethereum Blockchain. NFT CryptoKitties consisting of a virtual pet that the player could breed with others to create offspring with combined traits as new NFTs.The game made headlines in December 2017 when one virtual pet sold for more than US$100,000. CryptoKitties also illustrated scalability problems for games on Ethereum when it created significant congestion on the Ethereum network in early 2018 with approximately 30% of all Ethereum transactions being for the game.