CryptoKitties Explained

When people say blockchain or crypto, they most often associate those terms with money. For instance, Bitcoin is the first sound digital asset independent of intermediaries, UNI is one of the latest DeFi tokens made popular by DEXes, but a few years ago, not only finance-oriented dapps were admired.

To start building more wide-spectrum products on blockchain again, maybe we should recall the times when CryptoKitties were in demand. Because blockchain is not only about money, it can be fun too.

What are CryptoKitties?

Do you like rare baseball cards, vintage comic books or artefacts from The Last of Us? Then, the following piece is a potential threat to you since it’s all about a very tempting new type of collectible – virtual cats also known as CryptoKitties. If you’ve never heard of them kitties, they are not your regular cats, because, c’mon, which regular cat will eat Ethereum’s gas for breakfast?

CryptoKitties is a blockchain game that enables users to buy, breed, sell and collect virtual cats with unique Cattributes: eye shape, eye color, fur pattern, tail type, belly fur, eyebrows, mouth, chin, whiskers and expression.

A random user’s collection in the CryptoKittens’ Marketplace

What’s more interesting, the Genetic Algorithm used for breeding Furrever Friends is similar to how real biological genetics work. When you breed two kittens together, a new specimen arrives, a genetic combination of the two parents. The lower the generation of the cat is, the more expensive it costs, because the first-gen cats were hatched out in 2017 and there can be no more than 50,000 of them.

In December 2017, the game was so popular that it clogged Ethereum. The rumour has it that at the peak of the hype CryptoKitties had 1.5 million users who were responsible for $40 million worth of transactions. The most expensive kitten, Dragon, was sold for 600 ETH ($170k).

In 2021, you can buy the legendary Dragon for the same price, 600 ETH, although today it makes $805k, not $170k. Such a price is justified by Dragon’s rarity of traits, generation. reproductive downtime and of course reputation.


As of this writing, the average sale price for a regular kitten was $5-$6 (0.005 ETH). According to the whitepaper of the project, “the CryptoKitties brand is incredibly approachable to consumers. By using colourful palettes, cute cat puns, and cat humour, the brand stands out in a space that is typically dominated by lacklustre, business-to-business branding.”

CryptoKitties under the hood

Because CryptoKitties is the game built on Ethereum, to play it, you’ll need to complete a few steps.

Go to Chrome or Firefox, install the MetaMask Wallet, transfer some Ether to the wallet from an exchange, open the wallet and, then, go to the CryptoKitties Marketplace.

Every CryptoKitten is a non-fungible token, using the ERC-721 token standard, so it can be stored, created and sent with a smart contract. The ownership of the kitten, say, the non-fungible token, can be tracked, because every transaction such as the change of a kitten’s owner, is being written onto the blockchain! But it’s also the reason why the ecosystem usually asks for a small fee.

Now you get why Ethereum was clogged back in 2017 when the game was popular, right? Because everybody was buying and selling kittens in bunches.

The success of the game has spawned a host of crypto collectibles in the market from puppies and pandas to tiny monsters and cryptobots. But then, just as it happens with any hype, it slowly died out.

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