作者：James Au

《Tetris Battle》是2010年低调登陆Facebook平台的传统电子游戏品牌。现在，才过了1年多的时间，这款游戏便能够取得Facebook上两大巨头公司Zynga和EA游戏相当的成就了。

据AppData数据显示，《Tetris Battle》已经成为了Facebook上十大最受欢迎游戏之一，共拥有310万的日活跃用户（DAU），而其中有200万是前两个月新增用户。总部设于夏威夷火奴鲁鲁的开发商Tetris Online Inc.认为这款游戏将在2012年到达新颠峰，并希望能够在这一年达到500万至1000万DAU目标。如果成功实现了这一目标，《Tetris Battles》便有望挑战Facebook上最受欢迎游戏榜单首位。

Tetris-Battle-DAU(from AppData)

Tetris Online市场营销副总裁Casey Pelkey以及游戏设计副主管兼执行制作人Eui-Joon Youm在最近采访中分享了制作一款成功游戏的设计、发布决策和盈利策略，Tetris Online其它游戏以及对于《Tetris Battle》拓展游戏《Tetris Arena》的发展计划。

游戏玩法：多人游戏的变化

《Tetris Battle》的基本游戏玩法其实与早前的街机版本差不多，但植入了包含更多竞争元素的多人游戏模式。在“竞速”模式中，玩家会努力以最快速度消除40行的初始行数而获得第一；在“竞争”模式中，当一名玩家在模版中形成了一个或多个行列时，便能够在竞争者游戏区域增加新的障碍。

Tetris-Battle-Sprint(from insidesocialgames)

游戏机制同时利用了同步和异步多人游戏竞争模式。开发者似乎不想公布他们在《Tetris Battle》中使用的特殊开发方法，所以他们只说了希望让游戏在同步和异步竞赛中具有相同的感觉这一目标。玩家将与级别相同的竞争者相互对抗，而如果他们所进行的是即时对抗模式，便能够在屏幕上看到竞争对手的实际游戏玩法。当玩家是与Facebook上的好友共同游戏，那么他们面对的便是完全同步的竞赛模式，并且能够实行用户对用户的同步聊天功能。该公司为了维持游戏的良好性能而有意限制了同步游戏连接，但是Pelkey说道，“每天仍有无数玩家在玩这款游戏。”

Tetris Online利用了许多游戏机制以增加游戏的用户粘性，包括升级系统以组合具有相同游戏能力的玩家，并开启新的游戏模式。与其它社交游戏一样，《Tetris Battle》也设置了能量仪表，它会在玩家的游戏期间慢慢下滑，并在一段时间后或者玩家赢取利益时再次填满。“Daily Bonus Spin”机制通过奖励那些连续数日登录游戏的玩家特别道具而鼓励他们频繁重返游戏。

Tetris-Battle-Daily-Spin(from insidesocialgames)

增长和使用情况：80%安装量来自口头推荐渠道

与Facebook的其它游戏不一样的是，《Tetris Battle》并未使用强制性的好友添加机制——玩家只有向好友发送安装邀请才能够继续前进。Youm说道：“我们更关注游戏的核心玩法。我们的核心理念是如果玩家喜欢游戏，自然就会留下来，并真心邀请好友加入游戏。”

这也是为何这款游戏在发行后的前6-8个月间发展速度相对缓慢的原因。《Tetris Battle》最初发行于2010年7月，那时候它的增长速度较慢，且拥有较低的用户粘性，DAU/MAU比值一直在7-15%之间波动着。不过技术问题也是影响这一问题的障碍之一。

游戏的缓慢增长也有部分原因归咎于较低的安装率：只有55%的玩家愿意安装游戏应用并真正完成游戏。开发者认为，出现这一情况可能是因为许多Facebook玩家不习惯《俄罗斯方块》这种以键盘操作为主的游戏玩法，因为几乎所有社交网站平台上的游戏玩法都是以鼠标点击为主。为了解决这一问题，Youm和他的开发团队选择在第一个加载页面上呈现游戏的键盘指令，让玩家能够在游戏初期使用屏幕键盘控制游戏。如此，《Tetris Battle》的安装率迅速增加到80%。

这种设计和布局改变带来的影响在2011年4月表现得最为明显。据AppData数据显示，该款游戏的DAU/MAU比率从20%快速跃到了27%，随后更是直窜到35%（游戏邦注：对于Facebook游戏来说超过20%的DAU/MAU比值就算非常好的成绩了）。Youm认为，在2011年4月之前，《Tetris Battle》已经获得了足够的群体效应（大约50万的DAU），因此能够推动着这些玩家通过口头推荐而提高该游戏的安装率。根据Youm所说的，该游戏的安装数中至少有80%是来自于口头传播，更有趣的是，这一趋势仍在继续发展。

《Tetris Battle》安装率的提高还有部分应归功于包含了tetrimino砖块的病毒式机制，即玩家能够因此结合或者弥补额外的能量。例如当玩家邀请了Facebook用户加入游戏，他便能够获得更多机遇以赢tetrimino砖块。玩家也可以赠送tetrimino给Facebook好友，以此激励好友加入游戏。同时，玩家在《Tetris Battle》中的任何信息都会显示在好友的涂鸦墙上（Youm认为，这是一款基于技能的游戏，所以玩家会更愿意与好友分享自己的胜利）。除此之外，根据开发者的描述，那些接收了好友邀请的玩家将会投入100%的努力于最初游戏体验中，并慢慢变成游戏的忠实玩家。

近几个月来，随着Facebook新增了ticker功能（即好友动态轮播功能），进一步强化了游戏的病毒式口头传播效率，从而让《Tetris Battle》的成绩取得更加显著的提高。开发者希望Facebook用户通过点击相关的应用ticker更新便能够立刻加入好友多在的多人游戏中。他们认为这一设置能够普遍提高Facebook平台上多人游戏的发展。

根据开发者所提供的数据，这款游戏迄今为止同时在线人数的最高纪录是将近20万，而平时一天大约有10万名玩家会玩游戏。其中20%的用户属于核心玩家，即那些一天会玩1小时以上游戏的玩家。正如我们之前说到的，游戏有一个能量系统，玩家的能量将在30分钟后得到恢复；如此，玩家就必须为此等上1个小时的时间，或者他们也可以选择购买额外能量以继续游戏。因此核心玩家一天至少会玩两次游戏或进行游戏消费。

Tetris-Battle-login(from insidesocialgames)

盈利和用户分布情况

开发者表示，《Tetris Battle》与其它益智游戏一样，每日活跃用户平均盈利（ARPDAU）是1至2美分。这一盈利率在美国玩家身上是最典型的，而其它英语国家的公民（如澳大利亚，加拿大或英国）同样也能够带来较好的盈利。按照这一幅度，保守估计，《Tetris Battle》每个月的收益可能超过了100万美元。

《Tetris Battle》的盈利主要是围绕于能量，装扮，功能道具，如“装甲”——能够保护玩家在游戏失败时不至于排名下滑。总的来说，功能性道具能够增强玩家的游戏玩法，如加速他们每个砖块的移动，获取最佳盈利。对于20%的核心玩家来说，砖块的“快速下降”是最受欢迎的盈利道具。特殊优惠商品与本土化机制也都能够提高游戏的盈利率。《Tetris Battle》最近针对中国玩家推出了本土化版本的游戏，从而提高了来自于中国玩家的利益。

从用户分布情况来看，《Tetris Battle》的男性玩家和女性玩家的粗略比例是1：1；而用户留存率较高的群体是年轻玩家，也就是大约20-40岁的玩家。核心玩家（也就是那些每天会玩超过1个小时游戏的玩家）主要是男性用户。按国籍来看，因为Facebook的国际化扩展，这款游戏已经延伸到世界上的各个市场中去了（来自丹麦的玩家却占有非常高的用户比例，但原因并不明确）。

利用并保护Tetris品牌在Facebook上的发展

根据Pelkey，Tetris品牌名称已经成为吸引玩家第一印象的重要原因；但是，品牌并不能决定游戏的用户留存率，游戏玩法和用户体验才是关键。他对那些想要创造出知名品牌和游戏的开发者提了一点建议：“你必须先创造出一款足够优秀的游戏，”并且添加能够适应不同平台社交组件的功能：“例如在Facebook，你就不应该只是吸引玩家的注意，同时还要想方法吸引玩家的好友。”可以说，《Tetris Battle》是迄今为止街机游戏在Facebook平台取得成功的少有案例之一。

考虑到这点以及《Tetris Battle》的继续发展，有些人不禁好奇，这款游戏将如何面对越来越多“山寨”作品的挑战。关于这一点，Tetris的控股公司Blue Planet Software对于保护Tetris品牌免受抄袭者的侵犯已经非常有经验了。虽然游戏本身并不受版权法保护，但却可为游戏中的一些元素注册商标；Tetris的logo，主题歌以及tetrimino砖块都获得了法律保护。关于Blue Planet的保护策略还有一个例子，Facebook上曾有一款与《Tetris Battle》极其相似的游戏《Blockstar》，该公司在2007年合法收购了这款游戏。还有一个相反的案例是《Scrabulous》，这款复制了《Scrabble》的非授权网络版游戏最终遭到了版权所有者的控诉而被迫下线。

Pelkey表示，他们并不希望这么做，“与一款游戏抗衡将会花费我们更多时间，所以我们很庆幸能够与独立开发者（《Blockstar》）达成友好的共识。”该公司将收购的这款游戏“并入其官方游戏模式中，使它成为Tetris发展史中的一款游戏。”随后该公司还据此推出了《Tetris Friends》，该游戏获得了35万的MAU。

未来的计划：《Tetris Arena》，本土化战略

即将在2012年第二季度发行于Facebook的《Tetris Arena》是《Tetris Battle》中的一个同步玩法模式，现在正处测试阶段。它锁定核心玩家市场，《Tetris Arena》将以多人游戏和同步游戏玩法为主，让玩家能够在游戏中与好友更好地进行竞争。

这款游戏还将植入全球排行系统——这也是第一款采用这种系统的《Tetris》游戏。Tetris Online认为基于这种模式，《Arena》将能够吸引那些迫切需要证明自己游戏能力的核心玩家，另外还将引入spectator模式。该公司通过在Twitter上发布了《Arena》的解锁码以便玩家测试游戏。因为这一举措，《Tetris Battle》的Twitter帐号在短短2个月时间里获得了26万粉丝。

《Tetris Arena》的盈利模式也将与《Tetris Battle》不同，它将涵括更多功能性消费道具。因为它是《Tetris Battle》中的一个游戏模式，所以他们计划通过游戏内部交叉推广这项新内容。

2012年，该公司还计划推出西班牙，法国，意大利，德国等本土化版本，并每个月推出一种新语言版本。玩家可以使用相同的《Tetris Battle》ID打开这些新添加的语言版本，从而为该游戏吸引更多玩家。开发者发现，当游戏在特定国家开展本土化策略时，游戏的发展势头也会趋于强大，并且口头传播也同样奏效；所以他们将会好好利用本土化策略推动这种增长。

Tetris Online同样也计划在2012年推出另外一款非Tetris品牌的多人对抗游戏，而另一款将推出的《Tetris Stars》则是以鼠标操作为主的游戏玩法，更加休闲的Tetris游戏（游戏邦注：该游戏正进行公开测试）。

2012年：《Words With Friends》vs.《Tetris Battle》

2012年初，我们发现《Tetris Online》与一些大受欢迎的Facebook游戏都带有某些相同的特质。这些游戏包含《Words With Friends》（拥有790万的DAU，1600万的MAU），《Bubble Witch Saga》（400万的DAU以及1100万的MAU），《宝石迷阵闪电战》（310万的DAU以及920万的MAU）。与《CityVille》以及《模拟人生社交版》等类型的游戏相比，这类游戏增速明显更高。按照这种趋势，益智/街机游戏将可能领跑2012年的Facebook平台。

对Tetris Online来说，他们认为《Tetris Battle》在今后的日子里最直接的竞争对手是Zynga的《Words With Friends》。根据Youm所述，《Words With Friends》的优势是手机连接功能和交叉推广机制。而《Tetris》游戏却很难绑定于游戏平台上，特别是触屏的智能手机。此外，EA拥有《Tetris》手机版本的所有权，它将参与Tetris Online的所有手机游戏发布工作。不过Youm表示，《Tetris Battle》全球市场覆盖率远远高于《Words With Friends》，因为后者的主导范围只在于英语国家或罗曼斯语国家。

所有的这些策略性假设将在Tetris Online于2012年发布的《Tetris Battle》本土化版本（主要面向欧洲和西班牙国家的用户）中得到实践。不管怎样，2012年，该公司将努力抓住机遇，而改变Facebook平台上的竞争空间。Youm认为，对于开发者来说多人竞争游戏模式更加持久稳定，因为它始终明确了游戏的最终对象和游戏目的，而这也是其它游戏所缺少的优势。就像《Tetris》品牌在发行了30年以来一直繁荣发展一样，Youm相信只要玩家能够始终保持着对于竞争类游戏的兴趣，Facebook上的多人游戏也将能够持续兴盛。（本文为游戏邦/gamerboom.com编译，拒绝任何不保留版权的转载，如需转载请联系：游戏邦）

Inside Tetris Battle, Facebook’s top multiplayer arcade game

James Au? Jan 12th, 2012

Tetris Battle started out in 2010 as a quiet attempt to bring a classic video game brand to Facebook. Now, just over a year later, the game is on track to compete with the very biggest Facebook games from giants like Zynga and EA.

Already ranked among the top ten most popular games on Facebook as recorded by our AppData traffic tracking service, Tetris Battle currently enjoys about 3.1 million daily active users with 2 million of them arriving in the game within the last two months alone. Honolulu-based developer Tetris Online Inc. has set the sky as the limit for the game’s growth in 2012, hoping to grow the total player base of Tetris Battle to between 5 and 10 million DAU this year. If successful, this would place Tetris Battles in serious competition for the top spot of most popular Facebook game overall.

In this report, Tetris Online VP of Marketing Casey Pelkey and VP of Game Design & Executive Producer Eui-Joon “Ace” Youm share the design and deployment decisions that make the game an ongoing success, their monetization strategies, other Tetris Online games and future plans for Tetris Battle expansion Tetris Arena.

Tetris Battle gameplay: Variations of multiplayer

Tetris Battle’s basic gameplay is similar to the original arcade version, except played in several varieties of multiplayer with enhanced competitive aspects. In “Sprint” mode, players race to be the first to create 40 lines the fastest; in “Battle” modes, when a player forms one or more lines on their board, obstacles and hazards are sent onto the playing field of her competitors.

Gameplay makes use of both synchronous and asynchronous multiplayer competition. The developer prefers not to publicize the specific deployment method used in Tetris Battle, except to say that its goal is to make gameplay feel the same in both synchronous and asynchronous matches. Players are pit against competitors of a similar level and when competing in real time, they will see their competitors’ actual gameplay depicted onscreen. When playing the game with Facebook friends, matches are entirely synchronous and feature a live user-to-user chat feature. The company intentionally throttles live play connections to maintain good performance, but Pelkey says it still represents “a significant percentage of total games played each day.”

Tetris Online incorporates a number of mechanics to encourage continued engagement, including a leveling system which is used to match players with similar playing abilities, and to unlock new game modes. As with many social games, Tetris Battle also has an energy meter which is drained during play, but replenished over time or via monetization. A “Daily Bonus Spin” encourages regular play by offering players special items for playing the game over consecutive days.

Growth and usage: 80 percent word-of-mouth installs

Unlike many Facebook games, Tetris Battle does not employ a mandatory friend-adding mechanic in which a player cannot progress further unless they send game installation invites to their friends.

Instead, says Youm, “We focus on the core gameplay… our core belief is if [players] enjoy the game and stay there, they will invite their friends.”

This partly explains the game’s relatively slow growth rates in its first 6-8 months. Initially launched in July 2010, it first had slow growth and low engagement rates, fluctuating between 7 and 15 percent of DAU as a percent of MAU (or DAU/MAU). Technical issues were also a culprit.

The game’s slow growth was also due in part to a lower install rate: Only 55 percent of players would go from launching the app to completing their first game. The reason for this, the developer believes, is that many Facebook gamers were unaccustomed to Tetris’ keyboard-driven gameplay, since nearly all games on the social network platform are mouse-driven. To address this challenge, Youm and his team put the game’s keyboard instructions in the first loading screen and focused players on only using the game’s main key controls for the initial game. As a result, Tetris Battle’s install-to-play rate increased to 80 percent.

The results of this design and layout change became quite evident in April 2011. According to AppData, the DAU/MAU rate then leaped from 20 to about 27 percent, and then began trending toward 35 percent. (Engagement rates of 20 percent DAU/MAU or higher are extremely good for a Facebook game.) Youm also believes that by April 2011, Tetris Battle had reached sufficient critical mass (then about 500,000 DAU) that word of mouth began to drive strong adoption rates, with current players actively inviting their friends to play. According to Youm, installations based on word of mouth are “at least 80 percent… and the funny thing is, it’s increasing.”

Some of Tetris Battle’s growth is also attributable to a viral mechanism involving tetrimino blocks, which can be combined and redeemed for additional energy. A player who invites Facebook users gets more chances to win tetriminos. Players who are Facebook friends with each other can give each other their tetriminos, which creates incentive for friend invites. Tetris Battle also sees significant growth via updates on friends’ Facebook walls, where news on winning games and other Tetris Battle successes can be posted. (As a skill-based game, Youm speculates that players feel more encouraged to share Tetris Battle victories with friends, than non-skill game updates.) Further, the developer reports that players who come to Tetris Battle via friend requests are more likely to put a full effort into the initial on-ramping experience, and are therefore more likely to convert.

In more recent months, Tetris Battle has seen noticeable growth through Facebook’s launch of the canvas app ticker, which amplified the game’s viral word of mouth. The developer hopes that Facebook makes it possible for users to immediately join friends in a multiplayer session, just by clicking on the relevant app ticker update. Doing this, they believe, would increase general growth of multiplayer games on Facebook.

According to the developer, the game now enjoys a peak concurrency of nearly 200,000 players, and routinely averages about 100,000 players throughout the day. Twenty percent of the total playerbase is classified as core players, defined as those who play over an hour a day. As noted, the game has an energy system, which kicks in after 30 minutes; at that point, a player must wait for an hour to refill their energy (i.e. playing time), or purchase extra energy. Core players are therefore playing at least twice a day and/or monetizing.

Monetization and demographics

The developer reports that Tetris Battle earns close to the puzzle game average of 1 to 2 cents in average revenue per daily active user, or ARPDAU. (Tetris Online declines to state specific ARPDAU for their game.) That monetization rate is typical for the game’s US audience, they say, with other English-speaking countries (Australia, Canada, the UK) also earning good monetization. At this range and at a conservative estimate, revenue for Tetris Battle probably exceeds $1 million per month.

Tetris Battle’s monetization options center around energy, decorations, and functional items, such as “armor,” which protects a player’s rank on the game’s leaderboard from decreasing whenever a player loses a match. Overall, functional goods that improve a player’s gameplay, such as speeding up the movement of their game pieces, monetize best. For the game’s 20 percent core users, a “fast speed drop” of incoming blocks is the most popular monetized item. Special discount sales of goods also increase monetization rates, as does localization of the game. Tetris Battle was also recently localized in Chinese, which resulted in a revenue increase among Chinese-speaking players.

Demographically, Tetris Battle players are roughly split 50/50 by gender, and retention tends to skew younger; in this case, meaning players in the 20-40 range. Core gamers (those playing for over an hour a day) are more male. In terms of players by country, the game reportedly grows in tandem with Facebook’s expansion into the international market. (Players from Denmark, for unknown reasons, comprise a disproportionately large percentage of the user base.)

Leveraging and protecting the Tetris brand on Facebook

According to Pelkey, the Tetris brand name has been an important draw for first-time players; however, retention depends not on the brand, but gameplay and user experience. He applies this lesson in general advice to Facebook game developers involved with other well-known brands and franchises: “You have to deliver a great game, period,” he says. And that includes adding features to the game that leverage all of the platform’s social components: “In Facebook, you better deliver [a game] that has something extra, and not only engages the player, but engages their friends as well.” So far, Tetris Battle is among the rare examples of games from the arcade era to succeed on Facebook.

Given that, and the continued growth of Tetris Battle, some might wonder if it will face copy-cat competitors which frequently beset successful Facebook games. In this case, Tetris’ holding company, Blue Planet Software, has a history of successfully protecting the Tetris brand from imitators in the legal arena. While games in themselves cannot be copyrighted, elements of a game can be trademarked; in this case, the Tetris logo, Tetris theme song, and tetrimino playing pieces enjoy that legal protection. As an example of Blue Planet’s protection strategy, a Facebook game called Blockstar, which had a striking resemblance to Tetris, was legally acquired and co-opted by the company in 2007. This move contrasts the fate of Scrabulous, a Facebook imitator of Scrabble that was shut down by the board game’s rights holder.

Instead of doing that, says Pelkey, “To help reduce the amount of time our legal team spent on shutting this particular game mode down, we were fortunate to befriend the individual who programmed [Blockstar]”. The company went on to “embrace it as an official game mode, making it a part of the Tetris history.” It’s still available within Tetris Friends, with 350,000 MAU. (Before joining Tetris Online, Youm himself was developing a knock-off of the original Tetris for an Asian developer.)

Future plans: Tetris Arena, localization and beyond Tetris Battle

In the second quarter of 2012, Facebook should see the launch of Tetris Arena, a gameplay mode in Tetris Battle that’s now in closed beta. Aimed at the core gamer market, Tetris Arena focuses on multiplayer, synchronous play, in which players compete live using the same playing pieces.

Given that focus, it will also come with a global ranking system — the first Tetris title to have one. For this reason, Tetris Online believes that the Arena mode will draw core players hungry to prove that they’re among the very best at the game overall. Also reflecting the developer’s goal to present Tetris as a competitive sport, Arena will also come with a spectator mode. The company has been testing it on gamers by publishing the Arena game mode’s unlock code on Twitter. Since starting this activity, the Tetris Battle Twitter account has gained 260,000 followers within two months. The Arena game mode is entirely live play, but since it’s still in closed beta, it represents a smaller percentage of the daily games played; the company expects this to grow as the game is opened to more players.

Monetization for Tetris Arena will vary from the main Tetris Battle game, with more functional consumable items. Since the game exists within the main app, the company plans to focus early launch on in-game cross-promotion.

As noted, Tetris Online recently launched a Chinese-localized version of Tetris Battle, garnering improved monetization in Chinese-speaking countries. In 2012, the company also plans to release localizations of the game in Spanish, French, Italian and German, with one new language deployed each month. All these versions will exist within the same Tetris Battle app ID, which will therefore enjoy any growth these additions are likely to attract. The developer notes that the game tends to gain growth momentum when it’s made available in a given country, and word of mouth kicks in; localization should further drive this growth.

Tetris Online also plans to launch a second product in 2012, a head-to-head multiplayer game, which will not be Tetris branded. Another game, Tetris Stars, which combines mouse-driven gameplay with a more casual variation of Tetris, is currently in open beta; the developer is still developing its Q1 2012 plans for that title.

Facebook games in 2012: Words With Friends vs. Tetris Online

At the start of 2012, several top Facebook games shared some common traits with Tetris Online. Among these are Words With Friends (with 7.9 million DAU, 16 million MAU), Bubble Witch Saga (4 million DAU, 11 million MAU), and Bejeweled Blitz (3.1 million DAU, 9.2 million MAU). All currently enjoy strong growth, especially as compared to other games now topping the popularity charts, such as CityVille and The Sims Social, which have comparatively flat growth. Given these trends, it’s likely that puzzle/arcade games will emerge as 2012’s leaders on the Facebook platform.

For the part of Tetris Online, they consider Tetris Battle’s most direct competitor in the coming year to be Zynga’s Words With Friends. From Youm’s perspective, Words has the advantage of mobile connectivity and cross-platform play. By contrast, competitive Tetris games are difficult to deploy on phones, especially smartphones with touch screens. Additionally, EA holds the rights to mobile versions of Tetris and would need to be brought on as a partner for any mobile deployment of Tetris Online games. However, Youm argues that Tetris Battle has a more global reach than Words With Friends, with the Scrabble-like game probably limited in appeal to regions where English or Romance languages predominate.

These strategic assumptions will be tested as Tetris Online rolls out localized versions of Tetris Battle in 2012, aiming to cater more directly to European and Spanish-speaking countries. In any case, the company sees this year as an opportunity to transform the Facebook platform’s competitive space. Youm argues that multiplayer competitive games are more sustainable for developers, because unlike most other genres, there’s no clear end point where all the game’s content has been enjoyed. Just as Tetris the brand continues to thrive nearly three decades after launch, he believes multiplayer games on Facebook can thrive as long as people are interested in playing them against each other.

“The success of puzzle games gives people something to think about,” as Pelkey puts it. ”At the end of 2012, maybe there’s a different face of gaming in Facebook.”(source:insidesocialgames）