What is CryptoKitties?

CryptoKitties is a web based game built by Axiom Zen to bring blockchain technology to the general people. It gamifies interactions with the blockchain through the buying, selling, siring and breeding of digital kitties.

CryptoKitties are digital, collectible cats built on the Ethereum blockchain. They can be bought and sold using ether, and bred to create new cats with exciting traits and varying levels of cuteness.

How many Gen 0 kittys are there?

At launch, 50,000 “Gen 0” cats (colloquially referred to as “Clock Cats”) were stored in a smart contract on the Ethereum blockchain. These Clock Cats are now distributed automatically via smart contract at a rate of one cat every 15 minutes. Each cat is sold by auction.


CryptoKitties are unique in appearance, with a distinct visual appearance (phenotype) determined by its immutable genes (genotype) which are stored in the smart contract.

Two CryptoKitties can breed to produce a new cat that is the genetic combination of its parents. Anticipating the outcome is exciting and the possibilities for new and rare genetic makeups of a CryptoKitty are endless. In each breeding pair, one cat acts as the sire and will have a recovery period before it can breed again. The second cat incubates the kitten, during which time it cannot engage in another pairing. There is no limit to the number of times a CryptoKitty can breed, but the recovery and gestational period increases the more they mate.

Why is this cool?

CryptoKitties is the world’s first game built on the Ethereum blockchain. It makes the blockchain approachable for the everyday consumer and brings us but a small step closer to widespread adoption of cryptocurrencies and blockchain technologies.

Does it cost to play?

Yes. CyrptoKitties requires a MetaMask wallet with ether in it. Here’s a guide on how to buy Ether on Coinbase, install MetaMask and get started.

Good kitties (rare, under gen 10) run at about $28 per kitty. You also have to pay transaction fees (gas) for miners to execute your request on the blockchain.


Every play you make in the game—buying, selling, putting up for sire, breeding—must be entered and validated in the blockchain. Miners (real people who love making super powerful computers) execute your request until it’s successfully completed.

Unlike our current payment systems, Ethereum transactions do not happen and complete in real time. This means that you have to put in the request, wait for the transaction to happen, get the confirmation of success, and THEN see your updated activity in CryptoKitties.

Can my requests fail?

Yes. If you do not allocate the right amount of gas (small amount of Ether to make the transaction happen), the miner might run out of gas and your transaction will fail. If a transaction fails, you lose the Ether you paid to the miner. The best way to calculate the right gas limit at the right price is by checking this ETH Gas Station‘s recommended price and gas limit before submitting the transaction.

This doesn’t sound fun anymore…

It’s SO MUCH FUN! Yes, there are areas of growth, and this is probably the worst possible way the game will run (it will only get better from here, unless everyone gets tired of failed transactions and abandons ship).

If you’re curious about gaming on blockchain technology, want to understand the Ethereum Network and apps running on it a bit better, or just want to own one of the adorable cyrptocollectible kitties, then you should absolutely check it out.

Ready freddie? Here’s a step-by-step guide on how to get started.

If you’re looking to make money, you can also check it out, but the value of kitties is not backed by any source, the price fluctuates based on the amount people are willing to pay for the kitties. It’s also easy to forget that something that looks pretty cheap, like a kittie costing you just 1 Ether is actually costing you $450 USD. Just keep this in mind, and happy meowing!

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