CryptoKitties

CryptoKitties is a cat collection and breeding game that uses the Ethereum blockchain network to verify ownership and value of the virtual pets. Each cat's appearance is based on a complex DNA system that determines "cattributes" such as fur color, patterns, eye shape, etc. When two cats are bred, their offspring inherits some combination of these genes. If the parents have compatible genes, there is also a chance for mutations to occur. In such a case, the offspring will end up with a trait neither parent had. New genes are often introduced to the game through this mutation system. Cats can be sold to other players for Ether, of which the developers will take a cut. Ether fees are also paid to breed cats or transfer ownership.

For limited times, Purrstige traits may be available. These can only be expressed by a cat that inherits specific gene combinations. A similar method can produce Fancy cats, which display none of their inherited genes but instead have unique artwork. On rare occasions, a Fancy cat can have an alternate coloration called a shiny. Both Purrstige traits and Fancy cats can only be bred within specific time periods, and once that period is up, cats can't be born with these traits even if they inherit the right gene combinations. Two final categories of cats, Exclusive and Special Edition, have unique artwork and cannot normally be bred. Instead, they are either sold or given away by the game creators, or otherwise produced under extremely unique circumstances.

Other developers can create games or applications in the KittyVerse, which allow for new ways for players to use their CryptoKitties. Applications allow for additional features such as dressing up the cats or analyzing their genome to find recessive genes. Players of KittyVerse games can use their own kitties as characters.