• 3000+ writers
  • From all 50 states
  • Top 4% of all who apply
Entertainment & Gaming

CryptoKitties: Everything You Need to Know

By a Verblio Writer

(987 words)

CryptoKitties introduced cuteness to the world of cryptocurrency, serving as the very first game built on the Ethereum network. Although this game created a fun and specific application for NFTs, it also revealed that the Ethereum network was far from “purrfect” by highlighting certain issues with the platform, particularly those around Ethereum’s scalability.

In this article, we’ll go over what CryptoKitties is and how it works, along with where this game stands today.

What Is CryptoKitties and How Does It Work?

CryptoKitties is a blockchain game that enables users to collect, breed, and sell digital felines in exchange for real currency. Each cat in the game is unique to the owner, preventing others from replicating it. Axiom Zen, a group of developers located in Vancouver, initially created CryptoKitties and launched it in 2017. Since then, the game has become increasingly popular, with some people reportedly making a lot of money through this game.

The game operates on the Ethereum network in the form of a decentralized application (dApp), meaning that no single developer or entity actually owns the game.

Individual CryptoKitties are the cats bred and traded in the game. They’re available in two sexes: dames and sires. Each cat comes with its own 256-bit form of genetic makeup that dictates which “cattributes” the cat has. These physical attributes include the cat’s fur and eye color, the cat’s fur pattern, its eye and mouth shape, and the indicator of its rarity known as its “purrstige.” If users breed two CryptoKitties, the KittyOwnership smart contract will generate a new CryptoKitty that features the “cattributes” of its parents in a unique combination. After breeding a pair of CryptoKitties, there’s a cool-down period, after which users can then breed the two cats again to create a new CrytoKitty, with the ability to repeat the process endlessly. Users can then sell their cats for real money.

Like real animals, CryptoKitties can also undergo mutations known as “mewtations.” These started when genes that didn’t exist in the first generation of CryptoKitties developed as a result of a mutation. CryptoKitties with mewtations can belong to different types of tiers that influence their value. For example, the first cat that experiences a mewtation receives a diamond gem. The second to tenth cats that receive a diamond cat’s mewtation receive a gilded gem, with subsequent mewtation tiers receiving amethyst and lapis gems. With each tier, the value of the CryptoKitties increases.

What Happened When CryptoKitties Went Viral?

CryptoKitties essentially launched the popularity of NFTs. CryptoKitties were the first type of NFTs to explode in popularity, at one point actually “breaking” Ethereum by accounting for nearly 95% of blockchain transactions. In the process, CryptoKitties flooded the market and contributed to a dramatic increase in the gas transaction fees on the Ethereum network.

As a result, CryptoKitties helped show that Ethereum requires some additional modifications to improve its scalability, as the blockchain struggled to handle the increasing demands of the NFT industry and decentralized finance (DeFi). 

The Relationship Between CryptoKitties and Ethereum

Similar to genes, CryptoKitties use unique numbers to create new equally unique CryptoKitties. As a result, no two CryptoKitties are the same due to the combinations that the Genetic Algorithm (GA) creates. Ethereum’s smart contracts contribute to this creation.

Unlike bitcoin, which uses an external account to make a transaction, Ethereum uses either external or contract accounts. Contract accounts don’t have a single owner, though they have a designated address used to complete transactions. Additionally, these contract accounts contain code that runs with every transaction performed, with a miner running it to validate the transaction. 

When it comes to CryptoKitties, there are multiple contract accounts or smart contracts that come into play:


The KittyBase is the smart contract where CryptoKitties codes are stored on the public blockchain.


This smart contract dictates who has ownership of the unique CryptoKitties created. After creating a CryptoKitty, it’s impossible to switch it with another without first altering the inventory value. KittyOwnership helps maintain the unique value of every kitten, although two kittens can share the same value.


The KittyAuction smart contract enables individuals to sell kittens to other CryptoKitties players. Additionally, players can enable their kittens to breed with another player’s kitten to create a new unique CryptoKitty.


This particular smart contract allows for crossover to take place and for two CryptoKitties to breed. In doing so, the code from both parent kittens combines to form a new original kitten.


Another type of contract is KittyMinting, which allows for the continuation of the CryptoKitties community through multiple generations. Through this contract, the first generation of CryptoKitties called gen 0 could lead to future generations.

The Status of CryptoKitties Today

In 2019, Ubisoft and Warner Music Group collectively invested a total of $11 million. Combined with the move to Flow blockchain, CryptoKitties has allowed for increased reach and overall scalability, keeping it popular into today.

CryptoKitties continues to expand in 2022, achieving a total of $173 million worth of sales, which translates to more than 67,630 ETH, according to KittyHelper. There are currently around 1,200 active monthly players, with nearly 1,000 new players added every month. Based on these and other stats, it is likely that CryptoKitties is only going to expand even further over time. 

What CryptoKitties Means for the Future of Cryptocurrency and NFTs

The continued growth of CryptoKitties has shown how resilient these and other NFTs can be, despite the game’s exposure of certain issues regarding scalability and efficiency on the Ethereum network. While CryptoKitties’ spread contributed to a congested network along with steep gas fees, moving over to the Flow blockchain gave CryptoKitties the chance to adapt and continue developing. Other asset collections have followed suit and surged in popularity as well, including CryptoPunks and CryptoCats.

The development and popularity of CryptoKitties and other types of NFTs indicate we’ll likely see many similar asset collections in the future, all of which will help build the next generation of the cryptocurrency industry.

Questions? Check out our FAQs or contact us.