作者：Daniel Cook

1、由炼金术衍变而来的化学

“炼金术士们非常清楚，在化学变化过程中，就算是在物理特性和外表发生变化最显著的情况下，往往有些“东西”是不变的；也就是，那些实质包含某些“法则”，而这些“法则”隐藏在许多表像之下，通过特定的操作显形。”

我最近突然读到一些关于炼金术的描述。这种令人欣喜若狂的伪科学终于在近千年的演变中成为我们今天所看到的化学。有那么一瞬间，我认为作者其实是在描述游戏设计中的艺术现状。

每一次当我坐下来细细享受一款经典游戏，如《俄罗斯方块》或《超级马里奥兄弟》带来的乐趣时，我似乎看到隐藏在游戏玩法之后的简洁又清晰的结构。我坚信，建立在人类心理学基础之上的高级机制和预测性要点，就像一颗鲜活的心脏，隐藏在每一款成功的游戏的中央，有力地击打起伏着。

如果我们将这些系统编纂起来，然后将其转变为一种适用于游戏设计的实用技术，会怎么样呢？

科学未出现的时代

“纵观这个法则的发展历史，炼金术士竭力理清其性质，然后在他们的化学实验结果中窥探到一些规律和道理。可是，不纯净或品质不佳的试剂、定量测量的缺乏和命名上的混乱及前后矛盾，总是干扰着化学实验。”

从历史的角度上讲，理解游戏的过程往往被无数的因素所限，如混乱的实验实践、对不可靠的游戏理论的依赖和令人迷惑不解的术语。我们仍然是游戏行业中的炼金术士，我们的游戏由二分不纯净的剧情、一分受污染的玩法和三分市场迷惑组成。

作为一种产业，我们必须越过那只挥舞着现代游戏设计的神秘的手。制作、测试和改善游戏设计实用模型（游戏邦注：从可观察的操作特征上建立起来的），现在已经成为可能。我们可以描述玩家的活动和游戏的反应。最近，我们已经开始努力理清玩家对某种刺激有反应的原因，也能够创造出可以预测玩家的愉悦和挫折情绪的模型。

本文将描述其中一种模型。

对于游戏设计师，我们抱着更大的希望，就是将我们的炼金技艺转移到游戏设计科学的构建之中。我们现在通过嗜好、猜想和对既定形式的盲从来构成游戏。构建一个可测试的游戏结构模型为游戏的平衡、原创的游戏设计和拓宽游戏在其他领域的运用拉开了一道新的门。

由最初的炼金术士演化而来的基础化学，成为划时代的利器，我们因此得以创造出一个大大超越了我们的前辈，那些炼金术士们所想象的科技新世界——塑料、引擎、纤维、能源等使我们的生活发生了翻天覆地的变化。因此，隐藏在游戏制作背后的基本科学原理，是值得我们竭尽全力去破解的密码。

2、游戏设计模型的基础

化学建立了物理原子的模型，正是这种可测量的模型将其本身从炼金术中分离出来；与这种分离不同，游戏设计的科学将其与人类心理学，这种可测试模型相结合。

许多定义游戏的尝试将关注焦点放在游戏的机制元素，如系统允许玩家进行的原始活动或玩家操作的标识符号。这是一种将游戏当作独立逻辑系统的观点。

对于任何游戏设计模型，结构和美学都是相当重要的两部分，但到头来，这种分析几乎没有洞察到游戏的乐趣所在。作为模拟活动的游戏，和玩家作为积极而变化的参与者之间，存在着有意义的交互作用，你却不能从你的游戏中看到这个真相。游戏不是数字系统。游戏是一种中心系统，其中总是充满人类、渴望、刺激和无尽的机智。为了准确描述游戏，我们需要一个可行的玩家心理模型。

玩家模型

我们的玩家模型很简单：玩家是有意识地或潜意识地受到驱使的实体，从而掌握高感知价值的新技能。成功地学会技能可以让玩家产生愉悦感。

我们先学会玩家模型中的三个重要概念。

技能

驱使型学习

感知价值

技能：

玩家用来操纵世界的行为就叫做技能。有些技能是概念性的，如导览地图，而有些技能是带有物质性特征，如用铁锤敲钉子。

驱使型学习:

一方面，玩是一种本能。在低级刺激环境下（我们不需要积极地从事与食物和居所相关的活动），人们一般会玩耍。厌倦或沮丧这类强烈的反馈机制会刺激我们采取行动。如果有空闲的时间，我们会像小孩子一样玩积木或玩偶，也会像成人一样投入到更复杂的兴趣中。这是我们需要有意义的刺激的一种迹象，所以，单独拘禁是对顽固罪犯的恶性惩罚。

另一方面，我们从学习中获得奖励。玩家称之为“有趣”的感觉来自掌握知识、技术和工具的活动。当你学会新事物，当你充分理解，当你能够运用所学来操纵你所在的环境向有利的方向发展，你就会感到快乐。

这种论断的支持来自神经科学的理论。Edward A Vessel是纽约大学神经科学中心的一个感知神经学家，他写道：

“当一种观念或信息被充分解释或理解时，这些“啊哈”时刻会导致大脑和身体产生大量化学物质，使我们产生愉悦的感觉。“得到”这种化学物质的感觉很好。当我们终于可以把我们的脑袋装满这种物质，这种观念就越深，我们的感觉也越好。”

在理解的一瞬间，大脑释放了一种名为内吗啡肽（endomorphin）的自然兴奋剂，它是一种信息传导化学物质，在结构上与吗啡类似。作为人类，我们不断地、激动地渴望着新信息。在某些情况下，你我称之为“好奇心”的东西可以理解为，我们的大脑在寻找下一种美味诱人的信息。

作为游戏设计师，我们要经常性地处理乐趣、厌倦和沮丧等。这些是生物现象，而不是一些神秘莫测的感觉。如果你对此话题有兴趣，我建议你去读读Raph Koster的书《A Theory of Fun for Game Design》。

感知价值:

玩家追求的更多的是具有高感知价值的技能。

玩耍大约有些相悖，它是一种高度实用的活动。我们对玩耍具有本能的冲动，这是由进化决定的，因为玩耍给我们提供了一个安全的机会去学习能够极大改善生活的行为，却不必受到生命的威胁。我们玩耍是因为我们希望从似乎毫无用处的活动中最终收获实用的东西。当然，当我们不能找到那种实用的东西，我们就中止那种玩耍活动。

感知的价值比客观测量出来的价值更重要。人类不是纯逻辑的动物。我们知道人们在如何权衡行为方面显示出一致的偏见。例如，当他们不能正确地评估胜算时，经常会冒一些莫名其妙的险。我们已经意识到，无论做什么决定，能纳入考虑的信息量总是受到大量限制。许多决定是根据“胆量”反应做出的，这种反应具有本身的下意识原则。

3、技能原子

现在我们有了玩家模型，我们可以描述一下于镓如何与游戏产生相互作用。

无论是否合乎标准，过去十几二十年，各种书籍对游戏的最基本材料已经有所描述；设计师们的闲聊中也涉及了这个话题。我取出了标识符、动词、法则、美学等基本材料，将其再次混合成一个独立控制的原子反馈环路中，即技能原子。其中，各个单元都描述了玩家如何获得新技能。

技能原子反馈环路是由四个主要元素组成的：

活动：玩家执行活动。对于技术原子的初学者，活动可能涉及按键。越是复杂的原子，越是要求玩家执行一连串活动，如处理复杂的迷宫。

模拟：根据活动，持续的模拟会升级。然后新的大门就开启了。

反馈：游戏为玩家提供某种形式的反馈，使玩家知道模拟如何改变状态。这种反馈可以是听觉性的、视觉性的或触觉性的。它可以是大爆炸体式的本能，也可以是一大块文本式的象征。

建模：玩家最终吸收了反馈，然后升级关于成功实践的精神模型。如果他们自认为取得了进步，他们会觉和愉快。如果他们掌握了一门新技能或其他工具，他们甚至会更加高兴。如果他们觉得自己的活动徒劳无功，他们就会陷入厌倦或沮丧之中。

以下图片是一个用于记录原子的速记表格。

例如，我们仔细分析马里奥的跳跃活动。

活动：菜鸟玩家按键。

模拟：游戏感应到（按键）活动后开始移动屏幕上的玩家角色马里奥。

反馈：屏幕向用户展示了马里奥跳跃的动态画面。

建模：用户形成一个表现按键活动导致跳跃的心理模型。

这个模型暗示着，这种原子往往需要多次循环，直到用户完全掌握。第一次用户得到的暗示是，某些有趣的事要发生了。然后用户再次按键以确认他们的理论，且马里奥再次弹回空中。此时，玩家笑了，因为他们意识到他们已经学会了一门有趣的技能，且日后将派上用场。

我们称之为“玩”的东西

“人类是会使用工具的动物……没有工具就没有人类；没有工具，人类什么也不是，有了工具，人类就是一切。”   ——19世纪作家Thomas Carlyle

根据技能原子学习一门新技术的过程中，玩家先试用它，然后在不同的环境下尝试，再看看是否达到实用的效果。这种半随机的探索类似孩子们从事的、典型的“玩”活动。例如，当一名新玩家掌握了跳跃的技能，你会注意到，他们几乎立刻就开始盼望着跳跃关卡的出现。表面上看，这是一种愚蠢又无聊的活动。事实上，在这种活动中的，我们观察到了出自人类本能的学习过程。

在尝试的过程中，玩家在某些环境下会发现有些东西能给他们带来有趣的信息，这些信息可能会促进他们掌握新技能。此时，你会看见，玩家的行为变得更加深思熟虑。一种心理模型开始在他们的心中成形。在刚才那个跳跃的例子中，玩家开始跳过一个平台。在掌握技术以前，需要多次循环新技能原子，这是非常普遍的现象。

最后，玩家使用一种现存的技能融汇惯通另一种技能。他们经历了快乐，又开始新一轮学习过程。

游戏机制的链锁作用

通过将我们的基本技能原子链接起来，从而创造一种名为技能链的定向图，我们可以直观地表示玩家的学习方法。

技能从一种原子经由链进一步流向另一种原子的活动中。通过连接越来越多的原子，你就构成了一个描述整个游戏的网络。每一项可期望的技能、每一次成功的活动、每一种可预测的模拟结果、每一点需求反馈都可以包括在简单却不失功能的网络形式中。

几乎所有你能想像得到的游戏，都可以用技能链来模拟它的一般性表示法。你的设计可以分解为许多种简单原子，这些原子再连接形成一个清晰又易读的游戏玩法示意图。因为技能链可以用玩家的体验描述来替代更多游戏机制，所以在游戏中发生的有意义事件的描述也更将丰富。

玩家与技能链之间的交互作用

玩家从一个原子移动到另一个原子，就像吃豆人（游戏中的人物）跟着一连串的点到达能量球。他们就这样，从一项技能移动到下一项，即使他们对最终目的地只存在一个模糊的概念。毕竟，吃豆子还是有点乐趣的。

人类局限性之一就在此时发挥作用了。玩家能够预测的新技能价值，不会比几个链上的原子所显示的多.一旦某种新技能的潜在价值落入我们的预测范围内,玩家就会追求这种技能。除了乐趣的体验，也许不会有长期的回报，但我们并不在意。一旦获得短期的奖励，我们就会假设我们的努力存在最终的益处。

如果你从更革命性的角度来看待，我们的行为确实很有道理。许多有用技能的掌握要耗费5到10年的时间。在教育早期，基本的玩耍活动，如评论哪个长虱子的女生，看起来特别傻。然而后来，我们却掌握了政治学、科学和动物交配仪式（就算是在长虱子的情况下）等等，对我们人类产生了重大的积极影响。

这里，这个假设性的故事得出的结论是，天生忙于长期性学习却没有立即回报的好玩人士，也正是最终精通了农业、狩猎和语言的人。这些人最终兴旺发达起来。而另一部分相反的人就相继走向灭亡。

然而，我们的大脑从来就没有演变到能够处理现代游戏的程度。一系列技能原子的存在只是为了娱乐我们，并没有真正地催生一种真实的、世界级的、崭新的技术。在我们孩童般天真的眼神里，游戏是一辆豪华的马车。分分秒秒的马车体验都符合我们的生物试探，而且马脖子上的铃铛听起来似乎也很和谐。所以我们不断地玩。为什么如此多的游戏以可怕的结局收尾，这使我们感到惊奇。

4、技能链上的原子的地位

当玩家开始游戏时，技能链提供了关于玩家状态的信息，这些信息都很实用。想象一下，技能链是一个点亮在玩家的发展中的仪表盘。任何时候，你都能识别出以下信息：

掌握级技能：最近刚掌握的技能。

部分掌握的技能：玩家不太认真对待、且还未掌握的技能。

未运用技能：玩家还没尝试过的技能。

积极性技能：玩家积极地运用的技能（游戏邦注：亦称磨损技能）

竭尽技能：玩家已经丧失运用兴趣的技能。

我们已经讨论了一些关于掌握级和部分掌握的技能。未运用技能需要单独做一下解释。如果一名玩家不能做出理解某项技能的必要活动，那个原子就永远不会被运用或掌握。如果玩家提早阻塞了链，下向流的掌握能力就永运不会触及下一个原子。

积极性技能和竭尽技能这两种状态值得进一步解释。

积极性技能：掌握一个原子的快乐，玩家只会体验到一次。精通之后，生物反馈系统开始生效，即抑制对再次运用这些相同的路径的愉悦反应，即原本刺激的运用现在变得相当无聊。

然而，玩家会继续将已经掌握的原子作为新工具来使用，以操作他们的世界。已掌握的原子就像一把悬挂在工匠腰间闪烁的新锤子一样好。新机会往往是以一个在技能链上进一步向下的原子的形式出现，这时，玩家利用他们的新技能来扩充自己的知识。

玩家有极大的耐心。他们乐意运用一个基本的技能原子上千次，只为掌握下一个更高级别的原子。玩家在《超级马里奥兄弟》中跳跃了无数次， 为的是达到链条下部更强大的技能。

已掌握的技能现在只是被运用于激活其他有点亮的灯的图标。

竭尽

玩家并不总是消除两个原子之间的隔阂。他们掌握新技术，使用了，却找不到任何乐趣。这就是所谓的竭尽。

例如，假设玩家按下跳跃键。他们执行跳跃，我们记录他们对技能的掌握情况。然而，这个特定玩家不曾想出跳来跳去有什么用。可能他们没有在接近平台的地方跳，也没有接到来自下一个原子的有趣反馈。经过一个短期实验之后，没有任何有趣的结果，玩家就彻底停止按跳跃键了。

当玩家竭尽一个特定的原子，结果就呈波状上升和下降到链条。

早期的竭尽

在以上例子中，“达到平台的原子”从来没被掌握。这项基本技能无效。在更深层次连接的技能链中，早期竭尽可以切断一大部分玩家的潜在经验。你可以想一想管理早期竭尽的学习曲线。

晚期竭尽

另一方面，技能链下向的晚期竭尽可以导致积极性技能贬值。

例如，假设我们在跳跃游戏中有一个平台，别无其他。玩家跳上平台，没有发现任何有趣的新活动，所以他们就不再跳上平台。这样，跳跃技能就会退化，因为如果玩家不需要跳上平台，为什么他还要不厌其烦地跳呢？

竭尽是通向可测验性的通道

如果我们的游戏不能抓住玩家的注意力，竭尽就是清楚的信号。竭尽在游戏的技能链上蔓延，它暗示了玩家不久就会离开这款游戏。玩家觉得无聊了、沮丧了、甚至愤怒了。

也许最重要的是，当单个原子发生竭尽时，我们可以测量出来。这样，作为游戏设计师的我们就可以定性地洞察某个设计如何影响游戏测试员。当你开始沿着其他技能状态追踪竭尽，你可以非常清楚、明确地看到问题区所在。凭借对技能链的仪表化，游戏测量表现，是一个有待进一步探索的丰富课题。

5、技能链上的先进元素

我们已经覆盖了技能链的基本元素及如何记录玩家的进程状态。在你开始构建你自己的技能链前，我们还需要以下几点：

已存在的技能：技能链如何启动。

不相干的事：我们如何表现现代游戏设计中的剧情和其他无用但令人愉快的方面。

已存在的技术

玩家带着初期技能开始游戏。这些技能是构成技能链的始点。准确预测这些技能对玩家在游戏的剩余部分的乐趣，会产生重大景响。

缺少正确的初期技能

如果玩家缺少预期的技能，他们将不能够参与到游戏的初期原子中。在关于跳跃的例子中，想象一个玩家没有意识到需要按下游戏手柄上的键来实现某活动。这样的例子看似荒唐，但，这是许多非玩家看到一款相当复杂的现代操作柄时所面临的尴尬。不少游戏设计默认玩家能够使用两个高精度的小模拟控制柄和一个多余的模糊按键来驾驭3D空间。没有这种技能的用户在还没看到大部分内容时就在沮丧中放弃了。

不要认为这种用户很愚蠢，这是非常重要的。他们有的只是不同的初期技能。作为设计师，我们的工作之一是保证玩我们的游戏的人能够掌握游戏的早期技能原子。最终，这种方法形成一份详尽的已存在技能清单，供定位玩家人群和围绕这些技能构建我们的早期体验。不要假定不会出现的技能。

已掌握的游戏传授技能

另一方面，如果玩家已经掌握了既有技能，学习早期原子的过程可能非常无聊。当一个已经玩过了大量硬核游戏的玩家，再玩一个需要10分钟航行训练的游戏，他们也会感到无趣。因为他们厌倦的脑子在适当的时候却没有做出反应，所有的奖励注释都令人生厌。如果游戏不能教给玩家任何新事物，玩家极有可能在早期原子阶段就进入竭尽状态。

锁定正确的已存在技能是一种平衡做法。如果你做出了正确的选择，你就能够做出一款受玩家欢迎的直觉型游戏。如果你错误地选择了，你就是让自己冒着受挫、厌倦和必然竭尽的风险。

不相干的事

游戏装载着剧情、场景和激发某种情绪或其他有趣但无用元素的意像。玩家从这种反馈中收获愉悦。我们可以利用一种特别类型的原子，即“不相干的事”来反映这个艺术的混合体。

不相干的事是指设计师自知不会引发有用的游戏内置技能，但仍然激发部分掌握的乐趣。当玩家得到信息线索，既有的玩家记忆力就被激活，大脑中开始贪婪地吸收这些线索。例如，许多玩家与“蘑菇”存在已有的联系。如果你处在某个年龄层次或某种自由化的背景，你可能甚至会拥有一件装饰着一两个蘑菇的彩虹色的T-shirt。当这类人第一次玩《超级马里奥兄弟》，一看到神奇的“小蘑菇”们，他们的情绪非常有可能被调动起来。他们脑中的技能原子就被激活了，之后他们开始自由联想为什么亲爱的宫本茂大神会把这种相反的文化引用放进游戏里。

当然，真相是，这里的“蘑菇”什么也不是。玩家有限的预测视野、来自游戏相关反馈的化学物质和玩家既有心理结构，这三者的结合足以形成一股玩家会乐于再次追求的乐趣。

“不相干的事”的缺陷在于，在他们的游戏中，大多数玩家很快就对这种手法精疲力乏了。你第一次看到“蘑菇”，你可能会觉得有意思。第二次看到，你可能就看穿它的本性了：一把开启另一种提升技能的钥匙。

6、结论

我们已经在本文中涵盖了相当多的知识。但愿这份图解能让你对如何利用技能链描述游戏有一个清楚的理解。

利用技能链

作为工具，我发现技能链略图极大地提高了我对游戏动作的理解，即游戏的缺陷和改进之处等。

形成技能链可以告诉你以下信息：

清晰定位玩家在游戏之初就需要的已存在技能

清晰定位玩家完成游戏需要的技能

定位需要反馈机制的技能

定位玩家在游戏中享受到乐趣的地方

当玩家进入“竭尽”状态时，向开发团队发出警报

为分析玩家陷入“竭尽”的原因提供概念框架

虽然制作技能链需要一定的实践，技能原子并没有那么难定义，比起编写一大片单元测试的代码，显然算不上负担。

拓展主题

技能链是一个深刻的主题，我们只不过描述了其功能的最基本方面。进一步探究这个主题需要：

在重复开发过程中使用仪表化的技能链

与传统交互设计相关的技能如何

技能链中的限时和其他奖励分配技术的作用

利用技述链来批评一般游戏

技能链的局限性

从炼金术士到化学

我相信，像技能链这样的模型能够帮助现代游戏设计提升意图和预测的水平。借助本文出现的概念，你可以开始把这个模型整合入你现在的游戏中，然后收集你自己的数据。我们这个小市场当中已经涌现了一大批聪慧的人物，他们可以升级这个基础起点，这是肯定的。分享你的所得，我们可以开始升级我们的模型设计。如果游戏设计师能够拥抱这个科学的进程，然后开始构建游戏设计的科学，那会怎么样呢？

过去的炼金术士，渴望炼出黄金。他们借助不准确的仪器和可疑的宇宙运行理论，疯狂地投入到实验中。现代游戏设计师变化也不大。那些人不只是为了营利，而是为了一个相当空想的梦想：创造一个让玩家感动、受启发的世界。我们从过去成功的游戏中剽窃秘诀，我们的偶然实验让玩家享受了片刻乐趣，就足够我们自己沾沾自喜了。我们站在引领人类和软件相互作用的尖端，却自知甚少。

只有对设计构建模块基础产生更深层次的理解，游戏设计师才有能力打破过去侥幸成功的束缚。我们利用来自可控实验的实用技术，可以快速创造有效的新游戏。当我们有了基础化学、基本测量系统和基础原子理论，也许之后我们可以不断做出更深入人心的游戏。

利用软件操作个人或团体的心理，是一件非常让人兴奋的事。短期以内，我希望深入理解技能链这类模型，以帮助我们突破现存游戏类型的约束，这样我们就可以做出更好的游戏、更强势的游戏。长期以后，目睹世界因我们曾改进的心理学技术而发生改变，这会非常有意义吧。（本文为游戏邦/gamerboom.com编译，如需转载请联系：游戏邦）

The Chemistry Of Game Design

by Daniel Cook

1. Moving Beyond Alchemy

“…it was clear to the alchemists that “something” was generally being conserved in chemical processes, even in the most dramatic changes of physical state and appearance; that is, that substances contained some “principles” that could be hidden under many outer forms, and revealed by proper manipulation.”

I recently happened across a description of alchemy, that delightful pseudo-science of the last millennium that evolved into modern chemistry. For a moment I thought that the authors were instead describing the current state of the art in game design.

Every time I sit down with a finely crafted title such as Tetris or Super Mario Brothers, I catch hints of a concise and clearly defined structure behind the gameplay. It is my belief that a highly mechanical and predictable heart, built on the foundation of basic human psychology, beats at the core of every single successful game.

What would happen if we codified those systems and turned them into a practical technique for designing games?

In A Time Before Science

“Throughout the history of the discipline, alchemists struggled to understand the nature of these principles, and find some order and sense in the results of their chemical experiments—which were often undermined by impure or poorly characterized reagents, the lack of quantitative measurements, and confusing and inconsistent nomenclature.”
Historically, the process of understanding games has been limited by numerous factors ranging from messy experimental practices, spiritual reliance on untested theories of play, and confused terminology. We are still alchemists of our trade, mixing two parts impure story with one part polluted game play with three parts market voodoo.

As an industry, we need to beyond the mystical hand waving that defines modern game design. It is now possible to craft, test and refine practical models of game design built from observable patterns of play. We can describe what the player does and how the game reacts. Recently, we’ve begun to crack open why players react to certain stimuli and are able to create models that predict pleasure and frustration.

This essay will describe into one such model.

Fundamental Science Forms The Future

Diagram 2: Condensation polymerization of Nylon

(a substance not available to alchemists)

The bigger hope is to move our alchemical craft towards the founding of a science of game design. We currently build games through habit, guesswork and slavish devotion to pre-existing form. Building a testable model of game mechanics opens up new opportunities for game balancing, original game design and the broader application of game design to other fields.
The advent of basic chemistry gave us tools to build a new world of technologies far beyond that imagined by our alchemist forefathers. Plastics, engines, fabrics, power sources revolutionized our lives. It is a worthy effort to crack the fundamental scientific principles behind the creation of games.

2. The Foundations Of A Model Of Game Design

Where chemistry separated itself from alchemy by building testable models of physical atoms, a science of game design concerns itself with testable models of human psychology.

Many of the attempts to define games have focused on the mechanistic elements of the game, such as the primitive actions that the system allows the player to perform or the tokens that the player manipulates. The approach has been to treat games as self contained logical system.

Mechanics and aesthetics are certainly important pieces of any model of game design, but in the end, such analysis provides little insight into what makes a game enjoyable. You end up with a set of fragmented pieces that tell you almost nothing about the meaningful interactions between the game as a simulation and the player as an active and evolving participant. Games are not mathematical systems. They are systems that always have a human being, full of desires, excitement and immense cleverness, sitting smack dab in the center. To accurately describe games, we need a working psychological model of the player.

Player Model

Our player model is simple: The player is entity that is driven, consciously or subconsciously, to learn new skills high in perceived value. They gain pleasure from successfully acquiring skills.

Diagram 3: The player follows clues to the acquisition of a new skill

Let’s dig into three key concepts in our player model.

? Skills

? Driven to learn

? Perceived value

Skill

A skill is a behavior that the player uses to manipulate the world. Some skills are conceptual, such as navigating a map while others are quite physical, such as pounding in a nail with a hammer.
Driven To Learn

Play is instinctual. In low stimulation environments where we are not actively pursuing activities related to food and shelter, people will begin playing by default. Strong feedback mechanisms in the form boredom or frustration prod us into action. Given a spare moment, we throw ourselves into playing with blocks or dolls as children and more intricate hobbies as adults. It is a sign of our need for meaningful stimulation that solitary confinement remains a vicious punishment for the most hardened criminals.1

The flip side is that we are rewarded for learning. The sensation that gamers term ‘fun’ is derived from the act of mastering knowledge, skills and tools. When you learn something new, when you understand it so fully you can use that knowledge to manipulate your environment for the better, you experience joy.

There is a reasonable amount of neuroscience available to support this claim. Edward A Vessel, a cognitive neuroscientist at the NYU Center for Neural Science writes:

“These “aha” moments, when a concept or message is fully interpreted and understood, lead to a flood of chemicals in the brain and body that we experience as pleasurable. It feels good to “get” it. The deeper the concept is, the better it feels when we are finally able to wrap our head around it.”

Upon the click of comprehension, a natural opiate called endomorphin, a messaging chemical in the brain similar in structure to morphine, is released. As humans, we are wired to crave new information constantly. In some sense, what you and I term curiosity can be interpreted as our brain looking for its next fix of deliciously fascinating information.

As game designers, we deal with the fun, boredom and frustration on a regular basis. It is good to recognize that these are biological phenomena, not some mystical or mysterious sensation. For more thoughts on the topic, I encourage you to have a quick read through Raph Koster’s book “A Theory of Fun for Game Design”

Perceived Value

Players pursue skills with high perceived value over skills with low perceived value

Play is, perhaps counter intuitively, a deeply pragmatic activity. Our impulses to engage in play are instinctual, selected for by evolution because it provides us with the safe opportunity to learn behaviors that improve our lot in life without the threat of life threatening failure. We play because we are built to expect the eventual harvesting of utility from our apparently useless actions. We stop playing when we fail to find that utility.

The perception of value is more important than an objective measurement value. Humans are not creatures of pure logic. We know people exhibit consistent biases in how they weight their actions. For example, they’ll often undertake bizarre risks because they are unable to properly evaluate statistical odds. We’ve also realized that people have substancial limits on how much information they can take into account when making any one decision. Many decisions are made based off highly predictable ‘gut’ reactions that have their own subconscious rules.

Chapter 3: Skill Atoms

With our player model in hand, we can describe how the player interacts with the game.

The basic ingredients of a game are, if not standardized, at least well described in a variety of books and rambling by designers across the past decade or two. I’ve taken the basic ingredients of tokens, verbs, rules, aesthetics, etc and remixed them into a self contained atomic feedback loop called a skill atom. Each unit describes how the player gains a new skill.

Diagram 4: The player follows clues to the acquisition of a new skill

A skill atom feedback loop is composed of four main elements:

-Action:The player performs an action. For a skill atom encounter by a new player, the action might involve pressing a button. More advanced atoms might instead require the player execute a batched set of actions such as navigating a complex maze.

- Simulation: Based off the action, an ongoing simulation is updated. A door might open.

- Feedback:The game provides some form of feedback to the player to let them know how the simulation has changed state. This feedback can be auditory, visual, or tactile. It can be visceral in the form of an exploding corpse or it can be symbolic in the form of a block of text.

- Modeling: As the final step, the player absorbs the feedback and updates their mental models on the success of their action. If they feel that they have made progress, they feel pleasure. If they master a new skill or other tool, they experience an even greater burst of joy. If they feel that their action has been in vain, they feel boredom or frustration.

A shorthand diagram that I find useful for recording atoms is as follows:

Diagram 5: Our canonical skill atom

For example, let’s dissect the act of jumping in Mario

Diagram 6: The skill atom of the player learning how to make Mario jump

? Action: An inexperienced player pushes a button.

? Simulation: The simulation notes the action and starts the avatar of Mario on the screen moving in an arc.

? Feedback: The screen shows the user an animation of Mario jumping.

? Modeling: The user forms a mental model that pressing the button results in jumping.

Implicit in this model is that the atom is often looped through multiple times before the user understand what it teach. The first pass may only clue the user that something vaguely interesting happened. The user then presses the button again to test their theory and Mario once again bounces up into the air. At this point, the player smiles since they realize they’ve acquired an interesting skill that may be of use later on.

This Thing We Call Play

“Man is a Tool-using Animal. . . . Nowhere do you find him without Tools; without Tools he is nothing, with Tools he is all.” – 19th century essayist Thomas Carlyle

Upon the acquisition of a shiny new skill from a skill atom, players experiment with it. They try it out in different environments and see if it does anything useful. This semi-random exploration is the classic ‘play’ activity that we see children perform. For example, when a new player masters how to jump, you’ll notice they’ll almost immediately start happily hopping about the level. On the surface, it is a silly frivolous activity. In reality, we are observing humanities instinctual process of learning in action.

In the course of experimenting, the player will occasionally stumble across something in the environment that gives them interesting information that might lead to the mastery of a new skill. At this point, you’ll see the behavior of the player become more deliberate. A mental model begins coalescing in their minds. In our jumping example, the player starts bumping against a platform. They may even reach the top of a platform. It is very common that skills acquisition requires multiple passes through the new skill atom before mastery is achieved.

Eventually, the player uses an existing skill to grok another skill. They experience a wash of pleasure and start the process all over again.

Chaining Of Game Mechanics

We can visually represent how players learn by linking our basic skill atoms together to create a directed graph of atoms called a skill chain.

Diagram 7: Two linked atoms

The skill from one atom feeds into the actions of another atom further down the chain. By linking more and more atoms in, you build a network that describes the entire game. Every expected skill, every successful action, every predicted outcome of a simulation, every bit of required feedback can be included in a simple, yet functional fashion.

Diagram 8: Sample skill chain for Tetris

(Click here for the full sized PDF)

A skill chain is a general notation that can be used to model pretty much any game imaginable. Your design can be broken down into dozens of simple atoms that link together to form a clear and easily readable map of how the game plays. The skill chain, with its ability to describe the player experience instead the mere mechanics of the game, provides a far richer description of the meaningful moments that occur during gameplay.

How Players Interact WithA Skill Chain

Players will travel from atom to atom like Pac-Man following a trail of dots towards the power pellet. They move from one skill to the next even when they have only a vague concept of the ultimate destination. Chomping up those dots is good.

One of our peculiarly human limitations comes into play at this point. Players are unable to predict the value of a new skill more than a couple atoms down the chain. As long as there a new skill with potential value within our prediction horizon, players will pursue it. There may be no long term payoff other than the pleasure of the experience, but we don’t care. As long as the short term rewards keep coming, we assume that there will be some final benefit from our efforts.

Diagram 9: Players have limited foresight

If you look at this from an evolutionary perspective, our behavior makes quite a bit of sense. Many useful skills take upwards of five to 10 years to master. During those early days of our education, the basic playful activities such as gossiping about which girls have cooties seem rather silly. Later on however, our mastery of politics, science, or in the case of the cooties, mating rituals, yields a hugely positive impact on our well being.

The just-so story here is that playful folks that instinctually engaged in long term learning with no immediate benefit were the ones that mastered agriculture, hunting and language. These folks thrived. Those that did not died off.

However, our brains never evolved to deal with modern games. The existence of a set of skill atoms that are tuned just to entertain us and that never actually lead up to a real world skill is something new to the world. At their most puerile, games are a grand hack. The minute by minute experience fits all our biological heuristics and sounds all the right bells. So we keep on playing. And we wonder why so many games have such horrible endings.

4.Status Of Atoms In The Skill Chain

A skill chain provides some rather useful information about the state of the player as they engage the game. Imagine that the skill chain is the instrumented dashboard that lights up with the player’s progress. At any point in time you can tell the following information

Mastered skills: Skills that have been recently mastered.

Partially mastered skills: Skills that the player is toying with, but has not yet mastered.

Unexercised skills: Skills the player has yet to attempt.

Active skills: Skills that the player is actively using. (aka the Grind)

Burned out skills: Skill atoms that the player has lost interest in exercising.

Diagram 10: Icons for skill status

We’ve talked a little bit about mastered and partially mastered skills. Unexercised skills are pretty self explanatory. If a player can’t perform the actions necessary to understand a skill, that atom will never be exercised or mastered. Mastery flows down the chain and if players are blocked early on, they’ll never each the further atoms.

The two states that are worth a bit more explanation are active skills and burned out skills.

Active Skills

The player only experiences the joy of mastery for an atom only once. After the moment of mastery, a biological feedback system kicks in that dampens the pleasure response to exercising those same pathways again. What was once exciting becomes boring.

However, players will continue exercising an already mastered atom as a new tool for manipulating their world. A mastered atom is as good as a shiny new hammer hanging from a workman’s belt. When a new opportunity comes up, typically in the form of an atom further down the skill chain, the player makes use of their new skill to advance their knowledge.

Players have enormous patience. They are willing to exercise a basic skill atom thousands of times in order to achieve mastery of a higher order atom. Players jump innumerable times in Super Mario Brothers in order to reach more powerful skillsets further down the chain.

A skill that has been mastered and is now simply being used to activate other icons is represented by the lit light icon.

Diagram 11: Active Icon

Burnout

Players don’t always bridge the gap between one atom and the next. They master a new skill, they play with it but fail to find any interesting use for it. This is known as burnout.

Diagram 12: Burned out icon

For example, suppose our player pressed the jump button. They performed the jump and we recorded their mastery of the skill. However, this particular player never figured out that how the jump might be useful. Perhaps they didn’t jump near the platform and receive interesting feedback on the next atom. After a short period of experimentation with no interesting results, the player stopped pressing the jump button entirely.

When a player burns out on a particular atom, the consquences ripples up and down the chain.

Early Stage Burnout

In the example above, the Reach Platform atom will never be mastered. The foundational skills are not in place. In a deeply linked skill chain, a burnout early on can chop off huge sections of the player’s potential experience. You can think of learning curves in terms of managing early stage burnout.

Later Stage Burnout

On the other hand, a burnout later on down the chain can devalue active skills.

For example, assume we have a single platform in our jumping game and there is really nothing on it. The player jumps on the platform, discovered no interesting new activities and so stops jumping on platforms. This, in turn, atrophies the Jump skill, because if the player doesn’t need to jump on platforms, why would he bother jumping?

Burnout Is Our Gateway To Testability

Burnout is a very clear signal that our game design is failing to keep the players attention. As you watch burnout creeps across a game’s skill chain, it is a signal that players will soon stop playing the game. They are becoming bored, frustrated and perhaps even angry.

Perhaps most importantly, we can measure when burnout occurs for an individual atom. This gives us, as game designers, unprecedented qualitative insight into how a particular design is performing with play testers. When you start tracking burnout along with the other skill states, you can visualize the problematic areas with great clarity and accuracy. The entire topic of measuring performance of a game through instrumentation of its skill chain is a rich topic for further exploration.

Diagram 13: Skill atrophy due to later stage burnout

5. Advanced Elements Of A Skill Chain

We’ve covered the basic elements of a skill chain and how to record that status of the player’s progress. There are only a few more pieces we need so that you can start building your own skill chains.
Pre-existing skills: How the skill chain is jump started.

Red Herrings: How we represent story and other such useless, but pleasurable aspects of modern game design.

Pre-existing Skills

Players bring an initial set of skills to a game. These skills always form the starting nodes of a skill chain. Accurately predicting this skill set has a big impact on the player’s enjoyment of the rest of the game.

Diagram 14: How pre-existing skill feed into initial skill atoms

Lack Of The Correct Initial Skills

If the player lacks expected skills, they will be unable to engage the initial atoms in the game. In our example about jumping, imagine a player that didn’t realize that you need to push the button on the joystick in order to do something. Such an example may seem ludicrous, but it is one faced by many non-gamers whenever they are faced with a freakishly complex modern controller. Many game designs automatically assume the ability to navigate a 3D space using two fiddly little analog stick and a plethora of obscure buttons. Users without this skill give up in frustration without ever seeing the vast majority of the content.

It is very important to realize that such users aren’t stupid. They merely have a different initial skill set. One of our jobs as designers is to ensure that the people who play our game are able to master the game’s early skill atoms. Ultimately this means making an accurate list of pre-existing skills for the target demographic and building our early experience around those skills. Don’t assume skills that may not be there.

Pre-mastery Of Skills Taught In The Game

The flip side of all this is that if players have already mastered existing skills, the process of mastering early atoms is likely to be quite boring. When a player, who has completed a dozen hardcore titles, plays a game sporting a 10 minutes navigational tutorial they become bored. All the reward notes are sour because their jaded brain doesn’t react at the appropriate points. If a game doesn’t teach the player anything new, the player is very likely to experience burnout on the early atoms.

Targeting the correct set pre-existing skills is a balancing act. If you choose correctly, you’ll end up with an ‘intuitive’ game that players enjoy. If you choose incorrectly, you risk frustration, boredom and inevitable burnout.

Red Herrings

Games are laden with story, setting, and imagery intended to evoke a particular mood and other intriguing but useless elements. Gamers derive great pleasure from this feedback. We can represent much of this mélange of artistry with the use of a special type of atom known as a red herring.

Red herrings are atoms that designer knows will never result in a useful in-game skill, but that still evokes the pleasure of partial mastery in the player. When the player experiences the information cues, existing player memories are activated and the brain greedily sucks up the clues. For example, many players have pre-existing associations with mushrooms. If you are of a certain age and a certain liberal background, you may even own a rainbow colored T-shirt that sports a mushroom or two. When such a person plays Super Mario Brothers for the first time, they are quite likely to perk up at the sight of magic mushrooms. A skill atom in their brain is activated and they begin free associating why might dear Miyamoto have placed such a counter culture reference in the game.

Of course, the reality is that the mushrooms mean nothing of the sort. The combination of the player’s limited prediction horizon with the chemicals gained from associating the in game feedback with their existing mental structure is enough to create a jolt of pleasure that the player will happily seek again.

The downside of Red Herrings in their games is that most players rapidly burnout on such sleights of hand. The first time you see the mushroom, you might think it interesting. The second time, you see it as its true nature: a key that unlocks another skill that helps you advance.

6. Conclusion

We’ve covered a lot of ground in this essay. Hopefully, the diagrams give you a good understanding of how to describe a game using skill chains.

Using Skill Chains

As a tool, I’ve found that skill chain diagrams dramatically improve my understanding of how a game works, where it fails and where there are clear opportunities for improvement.

Creating a skill chain provides you with the following information:

Clearly identify the pre-existing skills that the player needs to begin the game

Clearly identify the skills that the player needs to complete the game

Identify which skills need feedback mechanisms.

Identify where the player experiences pleasure in your game

Alert the team when and where players are experiencing burnout during play

Provide a conceptual framework for analyzing why players are experiencing burnout.

Though it takes a little practice, skill atoms aren’t all that complicated to define and are really no more of a burden than writing unit tests for a chunk of code.

Future Topics

Skill chains are a deep topic and we’ve described only the most basics aspects of how they function. Further topics of inquire include:

Use of instrumented skill chains as a tool in iterative development

How skill chains related to traditional interaction design

The role of timing and other reward distribution technique in skill chains

Critiques of common games using skill chains

Limitations of skill chains

From Alchemy To Chemistry

I like to imagine that models like skill chains will help raise the level of intent and predictability in modern game design. With the concepts in this essay, you can start integrating this model into your current games and collecting your own data. We’ve got some immensely bright people in our little market and it is almost certain that they can improve upon this foundational starting point. By sharing what you’ve learned, we can begin to improve our models of design. What happens if game designers embrace the scientific process and start build a science of game design?

The alchemists of ages past dreamt of turning lead into gold. They performed mad experiments with imprecise equipment and questionable theories of how the universe worked. Modern game designers are not really so different. Those not simply here for the sake of profit instead rally around equally fantastical dreams such as creating a game that makes the user cry or enlightening the world with games of politics or hunger. We crib cryptic notes from past successes and chortle merrily when our haphazard experiments manage to mildly entertain our audience. We are on the leading cusp of deep human / software interaction and yet we know so little.

It is only by gaining a deeper understanding of the fundamental building blocks of design that game designers with gain the power to break free from the accidental successes of the past. With practical techniques gained from controlled experiments, we will create radically effective new applications. When we have our basic chemistry, our basic systems of measurement and our basic atomic theory, perhaps then we can consistently build games that tap into the heart of human psychology.

The reproducible application of psychological manipulation of individuals and groups using software is big heady stuff. In the short term, I would hope that a deep understanding of models like skill chains help us crack open the rigid craftsmanship of existing genres so that we can build better, more potent games. Long term, it will be interesting to see what world changing uses we can find for our ever improving psychological technology.

An example of game chemistry in action

Here is a rough draft of a skill chain for Tetris. It is interesting to note that a game that is mechanically quite simple can possess an expansive skill chain.
? PDF (800k)

? Description of expert level Tetris skills

Relationship of Skill Chains to MDA (Mechanics, Dynamics, Aesthetics)

This is a question that has been posed on occasion. MDA is a game analysis framework put forth by Robin Hunicke, Marc LeBlanc and Robert Zubek. It is one of many descriptive techniques that catalog the elements of a game. The hope is that in the process of defining the pieces of a game, the designer will clarify their thinking about a design. This is certainly an admirable goal.

The major differences between the two approaches is that in MDA there is little attempt to model the actual player experience with the game. MDA analysis also fails to provide any objectively testable structure. With skill chains, you can always hook up logging software and observe where atoms light up and where they burn out. （source:gamasutra）