Getting started with CryptoKitties Part Two: Buying and Breeding

Apr 16, 2018 · 5 min read

Getting your first CryptoKitty

You’ve got ETH and Metamask installed, and you’re all set to start using CryptoKitties. So what do you do first?

Use the “Search” tab to look around the marketplace and find yourself some Kitties. If you’ve found a Kitty you’d like to buy, click on the cat and hit the “Buy now” button. A new page will open so you can double-check the Kitty you’re about to purchase. If everything seems in order, click on “OK, buy this Kitty”. You’ll be prompted with a MetaMask transaction window. Don’t click on any buttons yet — you need to understand a few things before moving forward.

What is a gas limit and a gas price?

This is a perfect moment to introduce you to one of our favourite community resources: This page has a detailed but concise explanation of gas, gas limits, and gas prices.

The most important part of your transaction is the gas price. This is a variable you can freely change to save a small amount of money. The lower your gas price, the longer it takes for your transaction to be confirmed by the Ethereum network. Be careful not to set your gas price too low; it might mean your transaction doesn’t get processed at all by the Ethereum miners (the people who process all transactions). ETH gas station can recommend a good gas price for the current amount of traffic. We recommend you check the site before you decide on a gas price for your transaction.

Don’t change the gas limit. The limit is generated by MetaMask. Lowering the gas limit means you don’t give the Ethereum miners enough computational power to process your transaction, which causes your transaction to “run out of gas” and fail.

Sometimes MetaMask suggests a really high gas limit, usually coupled with a warning that says “Gas limit set dangerously high. Approving this transaction is likely to fail.” If you see that message, something is wrong! The safest option is to reject the transaction and try again.

Once you’ve decided on a gas price for your transaction, click “Accept” on the MetaMask transaction window to send your transaction to the network. Within a few minutes, you should have your first Kitty! You‘ll get an email whenever your bid to buy or breed with a Kitty is successful. Your new furry feline will arrive in your litter in a jiff.


There are two ways to breed a new Kitty: breed two of your own Kitties together, or breed with a public sire. Best practice is to breed two Kitties of the same generation, since the offspring’s generation (gen) will be the highest generation of both parents plus one. If you breed a Gen 3 and a Gen 4 Kitty together, you get a Gen 5 Kitty. If you breed two Gen 3s, on the other hand, you get a Gen 4.

If you want to breed two of your own Kitties together, go to your litter and click on a Kitty you want to make the father (the Sire) in your breeding. This cat will show a “Breed” button. Click on that, then click on “Sire with my Kitties”. After that, you get to choose the Dame (or, the mother) for your breeding. Once you’ve selected a breeding pair, hit “OK, give them some privacy” to open a transaction window and let those Kitties make some magic.

If you want to breed with a public Sire, click on one of the Sires you found on the marketplace. Hit the “Breed now” button to select a Kitty from your litter to be the mother (the Dame). After selecting the Dame, hit “OK, give them some privacy”.

What’s up with this breeding fee thing?

You might wonder: “Why am I being charged more than the price of the Sire?”

Breeding comes with a breeding fee. This breeding fee does not go into our pockets. It goes to “autobirthers”, community-run bots and smart contracts.

Let’s get technical! Our smart contract (the software we’ve put on the Ethereum blockchain) was set up to allow people from the community to call a “giveBirth” function whenever a Kitty is due. This system was put in place so we’re not personally responsible for birthing the new Kitties. Anyone tech-savvy enough can call this function, which makes the birthings totally decentralized. Whenever someone successfully calls the giveBirth function, they get the breeding fee as a reward for helping out CryptoKitties (and the blockchain).

Fancy Cats

There’s a special kind of cat called a “Fancy Cat”. Fancies can be created based on a secret recipe of certain cattributes. There are a limited number of each Fancy Cat, and that limit is different for every Fancy. Any CryptoKitty that has all the traits from a Fancy recipe becomes a Fancy Cat until the limit is hit.

One of these Fancy Cats is called PussForProgress! PussForProgress has a limit of 1,920 cats. If your offspring had the following Cattributes before the limit was hit, it would have become a PussForProgress kitty: gerbil, peach, safetyvest and himalayan. (Note that the limit of PussForProgress has already been hit! Don’t try to breed this Fancy Cat, all you’ll get is an admittedly adorable Kitten.)

Selling or siring your CryptoKitties

Once you’ve got your paws on some CryptoKitties, you’re can put them up for sale or Sire them to the public. If you go to your litter and click on one of your Kitties, you’ll see the buttons “Sell” and “Breed”. Both of these buttons lead you to a page where you can create an auction. “Breed” lets you create a Siring auction, which means other players can breed with your Kitty through the Siring market. “Sell” creates a sale auction. Other players can find your sale auction on the marketplace. You get to pick the starting price, the ending price, and the duration of the auction.

If you’d like some help appraising your kitties, visit our Discord community, our official community chat. There’s a specific channel for Kitty appraisals! There are loads of wonderful people in there who would love to help you out with your future CryptoKitties endeavours.

That’s it! You should be well into collecting and breeding by now. If you still need help, we recommend checking the Discord community — but if you find yourself scratching your head even then, email us at


Collect and breed digital cats with CryptoKitties, the world's most successful blockchain game:


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Collect and breed digital cats with CryptoKitties, the world’s most successful blockchain game — built on the Ethereum network.


Collect and breed digital cats with CryptoKitties, the world's most successful blockchain game:

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