Blockchain Games: A Survey <s> I. INTRODUCTION <s> Blockchain technology has attracted tremendous attention in both academia and capital market. However, overwhelming speculations on thousands of available cryptocurrencies and numerous initial coin offering (ICO) scams have also brought notorious debates on this emerging technology. This paper traces the development of blockchain systems to reveal the importance of decentralized applications (dApps) and the future value of blockchain. We survey the state-of-the-art dApps and discuss the direction of blockchain development to fulfill the desirable characteristics of dApps. The readers will gain an overview of dApp research and get familiar with recent developments in the blockchain. <s> BIB001 </s> Blockchain Games: A Survey <s> I. INTRODUCTION <s> In the last decade blockchain technology become mainstream research topic because of its decentralized, peer to peer transaction, distributed consensus, and anonymity properties. The blockchain technology overshadows regulatory problem and technical challenges. A smart contract is a set of programs which are self-verifying, self-executing and tamper resistant. Smart contract with the integration of blockchain technology capable of doing a task in real time with low cost and provide a greater degree of security. This paper firstly, explains the various components and working principle of smart contract. Secondly, identify and analyse the various use cases of smart contract along with the advantage of using smart contract in blockchain application. Lastly, the paper concludes with challenges lie in implementing smart contract the future real-life scenario. <s> BIB002
T HE blockchain system  became one of the most promising technologies since late 2017, nine years after the release of Satoshi Nakamoto's famed Bitcoin whitepaper  . In addition to the classic application of distributed public ledger, blockchain is now recognized as the foundation of decentralized applications (DApps) BIB001 . Ethereum  , known as the Blockchain 2.0 platform, is designed to facilitate smart contracts BIB002 , which are open source programs that can be automatically executed without any centralized control. However, the blockchain ecosystem is still struggling with the lack of killer applications. In fact, the initial coin offering (ICO) has been the most public recognized DApp since Ethereum starts its token business. Nevertheless, numerous ICO scams and valueless "air tokens" brought a disreputable impression on the emerging technology. The digital game has the potential to be the rescue of the blockchain. It perfectly fits the nature of the virtual currency ecosystem since it does not have the data entry pollution problems that commonly exist in many other DApps. In fact, the blockchain system fulfills the ultimate dream of many game players: the items they owned in the virtual world are non-fungible, exchangeable, inheritable, and independent to the game service provider. In this paper, we would like to formally define the term of blockchain games: the series of digital games designed and implemented based on the nature of blockchain technologies. Following are the major benefits blockchain has brought to the game industry. Rule Transparency: Due to the transparent characteristic of blockchain data, players or third-party organizations can audit the smart contract based games rules, which was hidden in the centralized server in traditional games. The transparent game rules will enhance the trustworthy of the game operation. Asset Ownership: In traditional online games, the virtual properties, including credits, items, and avatars, belong to game operators since all data are stored in the game operators' server. In contrast, the blockchain game player owns their game assets, because all virtual assets will be bound to the players' own address, which allows the players to control and manage everything. The ownership enables the game assets to be independent of specific game operators, which allow the players to retain their digital properties and in-game relationships, even after the game stops its operation. Thanks to the ownership feature, virtual assets in the blockchain ecosystem have tremendous market liquidity. The possibility of asset trades across different games and blockchain platforms stimulates the players to better engage in the game economy. Moreover, the liquidity enables potential new profit model for game operators: the value of the assets will be increased if the demand surpasses the supply, which should be restricted by immutable smart contracts. The game operators may benefit from the value increase of the tokens they issued. Assets Reusability: Intrinsically, the blockchain is an open database that hosts data and executable programs. Game developers can leverage blockchain to design an ecosystem that allows players to reuse their characters and virtual items across different games. To this end, newly launched games can directly inherit game assets from the existing ones. User-Generated Content (UGC): UGC in traditional games are restricted in the specific game, thus, belongs to the game operator. In contrast, these contents can be preserved by the players, thus, has the potential to be shared among multiple games. This benefit will, in turn, encourage the players to participate in the construction of new content. According to the above advantages, the industry has started its venture on integrating blockchain into gaming systems. The Blockchain Game Alliance 1 was formed in September 2018 to explore alternative uses of blockchains in video games. In contrast, there is still a blank in academia to study the impact of blockchain on the future form of games. In this work, we survey the state-of-the-art blockchain games and analyze their trend from a statistic approach. The remainder of this paper is organized as follows. We briefly introduce the blockchain technology in Section II and illustrate the system architecture for blockchain game in Section III to provide an overview. Afterward, We survey the state-of-the-art blockchain games by categories in Section IV. We also perform data analysis to summarize and predict the future trend of blockchain games in Section V. Section VI concludes the article and envision the future of blockchain games.