CryptoKitties

CryptoKitties is a blockchain game developed by Canadian studio Dapper Labs. The game allows players to buy, sell, and create NFTs using on Ethereum. These NFTs represent virtual cats. 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. Dapper Labs was spun-off from Axiom Zen. Both companies are based in Vancouver, Canada. CryptoKitties is the first major game to use blockchains, and one of the earliest examples of a blockchain project designed for recreation. Players purchase, breed and trade virtual cats that have different visual features of varying levels of rarity. Players must purchase Ether cryptocurrency to join the game, and spend it to perform each breeding and trade action within the game. The virtual cats are breedable and carry a unique number and 256-bit distinct genome with DNA and different attributes (known as "") that can be passed to offspring. Several traits can be passed down from the parents to the offspring. There are a total of 12 for any cat, including pattern, mouth shape, fur, eye shape, base color, accent color, highlight color, eye color, and optional wild, environment, 'purrstige' and 'secret'. Other features like cool downtimes are not passed down, but are instead a function of the 'generation' of the offspring, which is one more than the 'generation' of the highest 'generation' attribute. A CryptoKitty does not have a permanently assigned gender. While they can only engage in one breeding session at one time, each cat is able to act as either matron or sire. There is a 'cooldown' time that indicates how soon the cat can breed again, which goes up with the number of breeds, capped at one week. The virtual cats are static images that can only be purchased, bred and sold. The game has no goal. CryptoKitties operates on Ethereum's underlying blockchain network. Each CryptoKitty is a non-fungible token (NFT).