New York: ACM (2019) 379–89. Use Cases for Other Industries The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. (C) The network shrinks in stage 3. p. 442–6. Cryptocurrencies, such as Bitcoin, show a positive correlation between their prices and the sizes of the user groups [13–15]. We find that a large number of players poured in during the 10th and 18th days since the game release and quickly exited in the following month. The congestion that has resulted has even forced CryptoKitties to raise birthing fees in the game: Due to network congestion, we are increasing the birthing fee from 0.001 ETH to 0.002 ETH. Among all the costs, the breeding fee is the highest, followed by the miner’s fee for the selling operation, and the miner’s fee for the breeding operation is the lowest. The actual in-game breeding and sale may not happen on the same day. Currently, the breeding fee is set at 0.008 Ether (approximately $4.69). CryptoKitties’s smart contracts. The newborn kitty will be transferred to the owner of the mother kitty. The Gini coefficient of accumulated revenue stayed at a high level (greater than 0.8). The decreases in average degree, network density, and average clustering coefficient result from early players entering the game and expanding the network. CryptoKitties was the first widely recognized blockchain game. For the kitty sold for the first time, the seller’s profit can be written as, where v is the price at which the kitty is sold, fbreed is the breeding fee, gbreed is the gas fee for kitty breeding, and gsell is the gas fee to sell the kitty. So spend wisely. 16. Creative Commons Attribution License (CC BY). FIGURE 3. Available from: https://techcrunch.com/2017/12/03/people-have-spent-over-1m-buying-virtual-cats-on-the-ethereum-blockchain/ (Accessed December 4, 2017). Figure 10 shows the probability of generating a positive profit by selling kitties each day. Since this time there is now a way to see some of the hidden Catributes. It’s not a mega-expensive way to get some cheap saleable NFTs in your wallet. â CryptoKitties (@CryptoKitties) December 2, 2017. The breeding fee varied over time (see Figure 1). In fact, almost all transactions with an amount greater than 100eth occurred in early December 2017, which corresponds precisely to the rise stage of the game. 2. 11503620). In: Xu JJ, Zhu B, Liu X, Shaw MJ, Zhang H, and Fan M, editors. In this way, the buyer initiates a request to the seller and sends the purchase fee to the Offers contract. This is the contract where we set the functions required for two kitties to breed and produce a new kitty. 6 We cannot rule out the possibility that the game publisher deliberately made the news that a special kitty has being sold at an extremely high price. It was in November 2017 that the ETH blockchain saw a sixfold rise in user activity because of the addictive nature, and huge aftermarket value of the virtual moggies, nearly crashing the whole ETH network. To fully consider the limitations of blockchain systems in the game design. (A) The average degree, (B) the non-zero in-/out-degree ratio, (C) the Gini coefficients of in-, out-, and total degrees, (D) the average clustering coefficient, (E) network density, (F) reciprocity, and (G) assortativity. Chen T, Zhu Y, Li Z, Chen J, Li X, Luo X, et al. However, when I actually go to breed my kitties, the breeding fee is .075 ETH? We’ve also open-sourced the SQL code behind the analysis if you want to follow along. Figure 9A shows that the cost break-down for breeding and selling increased sharply in stage 2. 1. where vmedian is the median price of kitties (excluding 0-generation kitties) sold on that day. Through further analysis, we find that the main reason for the rapid increase in the game popularity was the increase of public attention by media outlets, while the reasons for the rapid decline in the game popularity include the oversupply of kitties, the decreasing of player income, a widening gap between the rich and poor players, and the limitations of blockchain systems. The average cost of breeding and selling a kitty in one day can be written as, where fbreed is the average breeding fee, gbreed is the average gas fee for kitty breeding, and gsell is the average gas fee to sell a kitty through SalesAuction contract on a particular day. Breeding your own cats can be done by heading to your litter and choosing which cat should be the *Sire *(father). Chen T, Li X, Luo X, Zhang X. Under-optimized smart contracts devour your money. Cham, Switzerland: Springer (2017b). The average clustering coefficient c is used to measure the clustering degree of the network, which is defined as. 7200649) and CityU Strategic Research Grant (No. On the other hand, the increase in kitty price attracted more players to join the community. After entering the third stage, although the Gini coefficient of the revenue earned by players from selling and renting fluctuated, they all remained at a relatively high level (greater than 0.6). Same rate of dealing price will be charged to the buyers using the Offers contracts. Articles, Beijing University of Posts and Telecommunications (BUPT), China, Hong Kong Polytechnic University, Hong Kong, SAR China. If the player rents another player’s kitty, he has to pay the rent r and gas fee grent. Possible reasons include that current blockchain platforms restrict developers from implementing complex game functions, current developers are paying insufficient attention to the players’ gaming experience, and lack a competitive market in the blockchain game industry. p. 141–8. CryptoKitties are NOT cryptocurrencies. NEW YORK: IEEE (2017). Teoretically, suppose a player uses two of his own kitties to breed a new kitty and sell it at the median kitty price (excluding the 0-generation kitties) through the SalesAuction contract on the same day. 20. In this study, we aim to fully unveil the collective user behaviors in the game and the reasons leading to the game’s rapid rise and fall by analyzing blockchain transaction records. As previously mentioned, all functionality is available to anyone by interacting directly with the smart contracts on the Ethereum blockchain. Profit is an important motivation to encourage the players to stay in the game. In: Chi Play’19: Proceedings of the Annual Symposium on Computer-Human Interaction in Play; 2019 October 17; Barcelona, Spain. It goes without saying that the higher value Cats you buy in the 1st place, the higher value the offspring will be. an empirical analysis of player behavior in crypokitties. Ethereum in 2021 ($1200) As we enter 2021, the landscape for Ethereum couldnâ t be more bullish. We construct a temporal kitty ownership transfer network and analyze the varying network parameters in the four stages. The game publisher increased the breeding fee to 0.015eth and later adjusted it to 0.008eth. You can also bid on a CryptoKitty if it isn’t up for sale, but it’s up to the owner to decide whether they want to accept or not. 7. Is CryptoKitties Like Cryptocurrencies? Figure 6 shows the Google trend index of CryptoKitties and number of daily addresses related to CryptoKitties transactions. 14. But, it’s not that simple. The Gini coefficient of out-degrees decreased gently, indicating that even the seller/buyer ratio increased, the gap between sales volume among sellers was narrowing. Save my name, email, and website in this browser for the next time I comment. How to Buy CryptoKitties In: 2017 IEEE 24th international conference on software analysis, evolution and reengineering (SANER); 2017 Feb 20–24; Klagenfurt, Austria. Blockchain, emerged as the underlying supporting technology for Bitcoin [1], is a distributed ledger system providing non-tampering and traceability functionalities. Unless you were homeschooled or educated in a very non-secular institution, you should know that for nature to take its course you will need 2 kitties. For now, we will lay a meaningless tautology on you about gas, and say “it is what it is”. ving money in Towards saving money in using smart contracts. Dotted lines separates the stage 1, 2 and 3. Based on these contracts, players can trade or transfer kitties with other players and breed new kitties. When a kitty is rented out through the Siring Auction contract, the game publisher will charge the lender 3.75% of the rent as a handling fee. A few players earned most of the money from the game, while most can only get very little income, if any. The changes in the proportions of the three methods over time are shown in Figure 5. Huang Y, Wang H, Wu L, Tyson G, Luo X, Zhang R, et al. 17. The Eiffel Tower NFT auction on OVR ends soon! In: IEEE INFOCOM ’18 conference on computer communications; 2018 April 16–19; Honolulu, HI, USA. As shown in Table 1, the CryptoKitties game has five smart contracts: the Core contract, GeneScience contract, Offers contract, SalesAuction contract, and SiringAuction contract. Available from: https://www.reed.edu/economics/parker/s12/312/finalproj/Bitcoin.pdf (Accessed May 19, 2020). Once too many players have joined the game, the time needed to validate operations in the game takes too long, therefore sabotaging the players' gaming experiences. This will ensure your kittens are born on time! 21. Inf Sci (2019) 492:58–71. If you have a little ETH to spare and have time for a lot of fun and feline frolics, you should give it a go. The replacement of a large number of ERC-721 kitties with WCK resulted in a sudden fluctuation in the network structure. This Cryptokitties Marketplace Review gives you all the info you need before signing up: fees charged, type of NFTs to purchase, payment methods and much more. (2015), vol. Unless bid by a buyer or canceled by the seller, the kitty will remain in the SalesAuction contract. |, 2018 9th International conference on computing, communication and networking technologies (INCCCNT), Chi Play’19: Proceedings of the Annual Symposium on Computer-Human Interaction in Play, IEEE INFOCOM ’18 conference on computer communications, 10th International Conference on Web Information Systems and Technologies volume 2: WEBIST ’14, 9th International Conference on Applied Informatics, Cham, Switzerland: Springer International Publishing, 2017 IEEE 24th international conference on software analysis, evolution and reengineering (SANER), 2018 IEEE/ACM 40th international conference on software engineering: new ideas and emerging technologies results (ICSE-NIER), International conference on information security practice and experience, 4 Collective Behaviors of CryptoKitties Players, 5 Reasons for the Rise and Fall of CryptoKitties, https://github.com/jiangxjcn/Cryptokitties-analysis.git, http://www.bbc.com/news/technology-42237162, https://techcrunch.com/2017/12/03/people-have-spent-over-1m-buying-virtual-cats-on-the-ethereum-blockchain/, http://snap.stanford.edu/class/cs224w-2014/projects/cs224w-27-final.pdf, https://www.reed.edu/economics/parker/s12/312/finalproj/Bitcoin.pdf. 3. NEW YORK: IEEE (2018), 1–4. Guo D, Dong J, Wang K. Graph structure and statistical properties of ethereum transaction relationships. FIGURE 10. At first, the cooldown on breeding is only 1 minute, the more generations a cat has the longer its cooldown is. The network contains 104,514 nodes and 1,304,525 edges. Since December 4, 2017, the number of new kitty listings has significantly exceeded the number of kitties sold every day, resulting in a rapid increase in the number of kitties left on sale, i.e., stock inventory (see Figure 8A). Dotted lines separates the stage 1, 2 and 3. If their revenue from selling kitties becomes lower than the costs, the players’ enthusiasm will decline or even disappear. (B) The ratio of successful sale for kitties listed on each day. The number of kitties transferred through the Offers contract was always small. Cart / $ 0.00 No products in the cart. Although this is still a fiendishly entertaining and addictive platform, one cannot help but think that this detracts from the fun, unknown element somewhat. The price will not change after this period. The non-zero in-/out-degree ratio α=Nout>0/Nin>0 is defined as the ratio of the number of nodes with an out-degree greater than zero (Nout>0) to those with an in-degree greater than zero (Nin>0) in the temporal network. The average degree k¯=2M/N represents the average number of kitties transferred in and out of the addresses, where M is the number of edges and N is the number of nodes in the temporal network. Ethereum [2], also known as the blockchain 2.0 platform, further adds supports for smart contracts, which are programs that can be stored and executed on the blockchain system [3]. However, as the number of new players decreased and existing players quit, the Gini coefficient rose in the third stage and kept rising in the fourth stage. vol. Garrick Hillman, from the University of Cambridge, seemed to massively miss the point of what ETH is about with the following comment “CryptoKitties has become so popular that it’s taking up a significant amount of available space for transactions on the Ethereum platform, Some people are concerned that a frivolous game is now going to be crowding out more serious, significant-seeming business uses.” If he had taken the time to learn that ETH is an open-source, developers dream, created by our good friends Vitalik Buterin, Gavin wood now of PolkaDot fame, Charles Hoskinson, now of Cardano et al. Required fields are marked *. It was set to 0.002eth at the game’s release. 357. Figure 3 shows four snapshots of the network in each of the stages. doi:10.1145/3392155. Drawing from these observations, we advise on the designing of future blockchain games as follows. Tepper F. People have spent over $1 m buying virtual cats on the ethereum blockchain (2017). In the early days of the game, the ownership transfer of kitties was mainly realized through the SalesAuction contract. As I am a struggling writer, trying to make a name for himself in the hottest new market, since the great New Market fire of 12-March-1683, I have gone for the budget, starter Kitties, which start at a modest $5-6 US, on a serious note re the gas fees, if one is in no great rush to get their hands on their cats, when the sale is awaiting confirmation, go to advanced options and adjust your Gwei. For example, the transaction fee charged by the OpenSea trading platform is only 2.5%. Cham, Switzerland: Springer International Publishing (2018). Impact Factor 2.638 | CiteScore 2.3More on impact ›, Cryptocurrency Transaction Analysis from a Network Perspective #4 CryptoKitty Breeding. Whether one thinks it's the greatest creation ever, or doesn't understand how something so dumb is so popula 19. (A) The average breeding fee, gas fee for breeding, and gas fee for selling a kitty through SalesAuction contract on each day. The low throughput of Ethereum [21] has rendered that concurrent operations by many users are not feasible. Available from: http://snap.stanford.edu/class/cs224w-2014/projects/cs224w-27-final.pdf (Accessed December 10, 2014). Every time you breed a Kitty, you are required to pay a fee of 0.008 ETH, in addition to a transaction fee that varies based on Ethereum network congestion. We found that the public attention drew by the message that a special kitty was sold at an extremely high price eventually led to the explosive growth of game popularity. Soon after that, players began to breed new kitties and sell them to each other. Front. A midwife is also needed in this case. Breeding, genetics, and auctions take place in other contracts. 4. Everything you do in CryptoKitties has a cost. Tuesday, February 16, 2021. The seller can only receive 96.25% of the dealing price after deducting the 3.75% handling fee for the game publisher. Each Kitty has a “cooldown speed” — a mandated resting … Design a mechanism to narrow down the gap between the rich and poor and prevent the revenue from being gained by only a few players. The profit of a kitty sale on the same day can be written as. Breeding More Kitties. Consider participation rate as the ratio of the number of addresses that take part in a specific activity to the number of all addresses in CryptoKitties, buying kitties through the SalesAuction contract has the highest participation rate (84.6%), indicating that most players would buy at least one kitty from the official marketplace. (A) The numbers of new kitty listings, kitties sold, and kitties on sale in the market every day. Evolution of the network structural properties over time. Every breeding session includes a transaction fee and a birthing fee,currently the breeding fee is 0.008ether while the transaction fee vary. As such, go through this process twice. Chen et al. 2. Another way to breed your CryptoKitty is by using the Sire button in the Marketplace. I went to a Catholic school, Nuns do not give the best “Life Science” classes), your cat will lay its egg, as is natures way, your new kitty will hatch, and be yours to cherish, your CryptoKitty selection will be available on Opensea. There are nine types of transactions (see Table 2) related to the movements of kitties, including the trading, transferring, and the new birth of kitties. Every transaction sent to the Ethereum network requires ‘gas’; the gas fee is given to Ethereum miners. In addition, the breeding fee is also dropping, making it easier to justify breeding kitties of any rarity. 18. Lecture Notes in Business Information Processing. 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Down transactions on Ethereum ( 2017 ) breed your kitties a little privacy and paying your fee! Mainly realized through the SalesAuction, the breeding fee has been stable at 0.008eth contract & decentralized application (. The super team whom Axiom Zen put CryptoKitties under after launch ), have made impossible!