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以《愤怒的小鸟》为例解析游戏易用性标准

发布时间:2011-08-04 10:33:28 Tags:,,,,

作者:Kwasi Mensah

引言

当我试图为自己参与制作的游戏寻找到一种易用性标准时,我什么也没找到。虽然ablegamers.org 这类网站提供了关于残疾人游戏的论文和统计信息,我仍然找不到一个可以清楚参照的指导方针,以确保尽可能多的人能够玩我的游戏。我知道盲目遵循条款不是实现易用性的最佳方式,可是当我们有一个关于测试物品的标准清单时,游戏开发者的工作不是更容易开展吗?

我能找到的是接近的就是《 Web Content Accessibility Guidelines》。这是一系列关于制作网站和可访问内容应遵循的最佳实践原则。每一条指导都附带一个例子和解释。所以在这篇文章,我打算利用这些标准来解析最流行的手机游戏《愤怒的小鸟》,另外我还将展示以下标准是如何产生更好的易用性。

讨论范围

angry birds(from gamasutra)

angry birds(from gamasutra)

在截图里我没有显示《愤怒的小鸟》的社交网络菜单。我只关注你占击“Play”后会看到的内容。我假设这是绝大多数玩家在这款游戏里的体验。

一般玩法

相关指导:

指导1.2:提供基于时间的媒体选择。

指导1.4:保证用户容易看到、听到包括与背景分离的前景内容。

指导2.1:确保键盘操作能实现所有功能

指导2.2:给予用户充足的时间来阅读和使用内容。

slingshot_sized(from gamasutra)

slingshot_sized(from gamasutra)

《愤怒的小鸟》的核心机制是用弹弓把鸟弹出去打绿色的猪。猪可以用冰块、木头、金属或其他材料作掩护。有些鸟具有特别的能力。如,蓝色的小鸟可以分成三只,黄色的小鸟可以在半空中加速。

bluebird_sized(from gamasutra)

bluebird_sized(from gamasutra)

就是这样。游戏的机制就这么简单。没有时间限制,也不需要疯狂的操作组合。大多数现代电子游戏都需要用户作出“调整”反应,但这款游戏与此无关,所以,残障人士和完全不熟悉游戏的人都很容易上手。

运用多重图解提示来区分小鸟、猪和障碍物,Rovio在这方面做得相当好。因为小鸟和猪的轮廓和大小明显不同,这样就避免对色盲造成困扰。甚至是对正常人,这种变化也突出了对象之间的差异。

characters_sized(from gamasutra)

characters_sized(from gamasutra)

虽然这款游戏不能用键盘,不过单凭一根手指就能游戏了,所以也不需要所谓的“和弦”般的操作了——同时使用多个键/多根手指。这样,有移动性障碍的人,如患脑瘫或关节炎的人也能玩这款游戏。同时,“一根手指”也简化了游戏,使每个人都能立即上手。

无VoiceOver支持

相关指导:

指导1.1:为所有非文本内容提供文体选择,以便转换为人们所需的其他形式,如大号印刷体、盲文、语音或更简单的语言。

指导2.4:帮助玩家操作、查找内容和定位。

指导3.1:确保内容易读、易理解。

指导4.1:最大化当前和以后的用户代理商的兼容性,包括辅助技术。

苹果的用户界面技术使苹果软件实现了标记按钮、标签和其他带有易用性信息的UI元素的功能。当打开VoiceOver,即iPhone的屏幕阅读器,视力障碍的人就可以听到响亮的信息阅读声。这项技术为盲人进入现代移动世界打开了一扇大门。

然而,利用苹果的现成技术会使你高度依赖iPhone平台。幸好,Rovio及许多其他手机设备开发商运用了他们自己的跨平台UI技术。这样,在iPhone、Android和其他新兴手机平台也都可以很简单地享受游戏。但是,Rovio看起来并没有利用任何苹果的易用性技术,因为它的UI上没有标注任何启动VoiceOver的东西。虽然不存在真正的提供易用性信息的跨平台方法,WCAG(网页内容亲和力方针)建议作为惯例,应在代码中插入以下信息:

名称:元素名称

作用:干什么

值:当前状态

正如苹果的可用性代码所期望的那样,这种信息整齐地排列成行。以间歇菜单上的声音切换按钮为例:

soundoff_sized(from gamasutra)

soundoff_sized(from gamasutra)

名称:“声音开关”

作用:在有声和无声之间进行切换

值:当前声音状态是关闭的

像《愤怒的小鸟》这样以视觉为基础的游戏,VoiceOver支持并没有什么帮助。即使每一个标签和按扭都有标记且排列妥当,对于有视觉缺陷的人,拉动弹弓把小鸟弹向躲在障碍物后面的猪,这个简单的动作仍然是非常难实现的。我认为,应该让游戏从根本上实现易用,而不依赖VoiceOver的帮助,会更好一些。VoiceOver应该只是作为整体易用性的点缀。

用户界面

相关指导:

指导1.1:为所有非文本内容提供文体选择,以便转换为人们所需的其他形式,如大号印刷体、盲文、语音或更简单的语言。

指导2.2:给予用户充足的时间来阅读和使用目录。

指导2.4:帮助玩家操作、查找内容和定位。

指导3.2:确保网页的出现和操作稳定。

指导3.3:帮助用户避免和改正错误。

芬兰开发商却来挑战美国市场,Rovio肯定熟知转换游戏文本的要求。游戏的菜单依赖的是直观符号而不是文本。

pause_icons_sized(from gamasutra)

pause_icons_sized(from gamasutra)

用于关卡命名和注明数字的文本对游戏的理解并不重要。就算是重要的信息,如小鸟的次要技能,Rovio依靠描述性图片和优秀的关卡设计也能让玩家明白。

placard_sized(from gamasutra)

placard_sized(from gamasutra)

用符号代替文本,不仅可以更轻松地进行游戏本土化工作,还可以帮助阅读困难的人理解游戏和享受游戏。

Rovio还确保UI表达简单易懂。每一个重要功能都只有两个标注。间歇菜单只有5个排列非常整齐的按扭。因为游戏的关卡很小,重新开始也很容易,所以Rovio就没有必要设置允许玩家返回改错的“取消”功能。这样,游戏进一步简化了,且所有人都更容易上手了。

其他指导:

指导1.3:以不同的方式组织内容(如更简单的布局),但不遗落信息或丢失结构。

指导2.3:避免设计出可能引起画面“抽搐”的内容。

我不认为指导1.3有什么关系。如果应用VoiceOver支持,《愤怒的小鸟》就可以支持标准的VoiceOver操作。但是,当开启VoiceOver或Zoom时,考虑到如何处理输入的转换,使用弹弓就不太方便了。受到这种核心机制的妨碍,这款游戏会变得面目全非。

《愤怒的小鸟》中没有任何闪烁动画,这样就减少了“抽搐”风险。虽然“抽搐”很少由影像引发,但大多数发作的人直到第一次遭受“抽搐”之苦才知道他们很容易受影响。

结论

看来,WCAG确实在判断游戏的易用性方面开了个好头。它不仅包含了以上主要指导,还涉及成功标准的多层级别(判断你执行指导的程度)。欲知详情,请参阅《Web Content Accessibility Guidelines》。

大部分平台缺失的是屏幕阅读器支持。苹果在易用性方面处于领先地位,希望其他平台能紧随其后吧。移动游戏将越来越吸引非传统玩家,如果索尼、微软和任天堂还不能贯彻易用性标准,我会感到失望。

《愤怒的小鸟》的易用性与大多数这些指导密切相关,这是值得重视的另一点。这种指导不仅可以满足有特殊需要的玩家,还是判断游戏易用性的标准。(本文为游戏邦/gamerboom.com编译,如需转载请联系:游戏邦

Angry Birds and Accessibility Standards

by Kwasi Mensah

Introduction

While trying to look for a set of accessibility standards for the game I’m working on I couldn’t find any. While sites like ablegamers.org can give really useful papers and statistics about disabled gamers, I couldn’t find a clear list of guidelines to follow for making sure as many people as possible are able to play my game. While I understand blind adherence to rules isn’t the best way to achieve accessibility, game developers lives are a lot easier when we have a standard list of items to test against.

The closest thing I could find are the Web Content Accessibility Guidelines. They are a set of best practices that should be followed for making a website and its content accessible. Each guideline also comes with an explanation of the reasoning behind it. So for this post, I’m going to use these standards to break down the immensely popular mobile game Angry Birds made by Finnish developer Rovio. In the spirit of the Gamasutra article “Resetting Accessibility in Games” , I’m also going to show how following these standards leads to better usability for everyone.

Scope

I’m not including Angry Bird’s social network menus in this review. I’m only focusing on content you see after hitting “Play”. I’m assuming this is the vast majority of a player’s experience in the game. Also, I’ve only made it up to level 1-21 on my iPhone. I really like the game, I just have next to no free time.

General Gameplay

Relevant Guidelines:

Guideline 1.2: Provide alternatives for time-based media.

Guideline 1.4: Make it easier for users to see and hear content including separating foreground from background.

Guideline 2.1: Make all functionality available from a keyboard.

Guideline 2.2: Provide users enough time to read and use content.

The core mechanic of Angry Birds is using a slingshot to fling birds at green pigs. The pigs can be protected by ice, wood, metal, or other materials. Some birds have special abilities. Like the blue bird that can split into three and the yellow bird that that can boost its speed in mid air.

That’s it. The core of the game is that simple. No time limits or crazy combination of gestures needed. You don’t have to have the “twitch” reaction associated with most modern games. Since “twitch” is something you can only get from other video games, its lack in Angry Birds makes it usable not just for the disabled but by people who aren’t used to gaming at all.

Rovio does a good job off using multiple graphical cues to differentiate birds, pigs and obstacles from each other. By making sure the outlines and sizes of the birds and pigs differ significantly, they avoid confusing the color blind [1]. Even for the non-disabled, the variation helps enforce the difference between these objects.

While not playable by keyboard, the game can be played with only one finger. There’s no need for “chording”, having to press multiple keys/use multiple fingers at the same time. This helps people with mobility related disabilities like cerebral palsy or arthritis play the game. It also simplifies the game and makes it easier for everyone to pick up and play right away.

Lack of VoiceOver Support

Relevant Guidelines:

Guideline 1.1: Provide text alternatives for any non-text content so that it can be changed into other forms people need, such as large print, braille, speech, symbols or simpler language.

Guideline 2.4: Provide ways to help users navigate, find content, and determine where they are.

Guideline 3.1: Make text content readable and understandable.

Guideline 4.1: Maximize compatibility with current and future user agents, including assistive technologies.

Apple’s User Interface tech gives apps the ability to tag buttons, labels and other UI elements with accessibility information. When VoiceOver, the iPhone’s screen reader, is turned on it can then read that information out loud to blind users. This tech has opened up the world of modern mobile devices to the blind. [2]

However, using Apple’s off the shelf tech ties you to iPhone. Rovio, and many other mobile device developers, use their own cross-platform User Interface tech. It makes it easier to not only have a game on the iPhone but also on Andriod and other emerging mobile platforms. Rovio, however, doesn’t seem to use any of Apple’s accessibility tech since nothing in its User interface is tagged to work with VoiceOver [3]. While there is no true cross platform way for providing accessibility information, WCAG suggest always making the following available from code:

Name: The name of the element.

Role: What it does.

Value: The state its currently in

This information happens to line up nicely with what Apple’s accessibility code expects. Using the sound toggle in the pause menu as an example:

Name: “Toggle Sound”

Role: “Switch Between the sound being off and on”

Value: “Sound is currently off”

Its worth noting that in a game as visually based as Angry Birds, VoiceOver support is the least of its problems. Even if every label and button was tagged and setup properly, the act of pitching a slingshot to hurl birds at pigs behind obstacles is still fundamentally inaccessible to someone with a visual impairment. I’m learning that its better to make a game fundamentally accessible and not to rely on VoiceOver support to save the day. VoiceOver should be the icing on a cake of general accessibility.

User Interface

Relevant Guidelines:

Guideline 1.1:Provide text alternatives for any non-text content so that it can be changed into other forms people need, such as large print, braille, speech, symbols or simpler language.

Guideline 2.2: Provide users enough time to read and use content.

Guideline 2.4: Provide ways to help users navigate, find content, and determine where they are.

Guideline 3.2: Make Web pages appear and operate in predictable ways.

Guideline 3.3: Help users avoid and correct mistakes.

Being a Finnish developer developing for an American market, Rovio must have been very conscious about the need for translating any text in the game. The game’s menu doesn’t rely on text at all but on intuitive symbols.

The text that’s used for level names and numbers isn’t important for understanding the game. Even for crucial information, like the secondary abilities of birds, Rovio relies of descriptive pictures and good level design to teach the player.

The use of symbols instead of text not only makes the job of localization easier but helps players that have trouble reading but can still see well enough to play the game.

Rovio also makes sure to keep the User Interface very shallow. Every important feature is only two taps away. The pause menu only has 5 buttons on it leaving it very uncluttered. Since the levels are small and restarting them is so easy, Rovio doesn’t have to implement “undo” functionality to let players fix mistakes. This keeps the game simple which again makes it more usable for everyone.

Other Guidelines

Guideline 1.3: Create content that can be presented in different ways (for example simpler layout) without losing information or structure.
Guideline 2.3: Do not design content in a way that is known to cause seizures.

I don’t think Guideline 1.3 is relevant. If VoiceOver support was implemented Angry Birds could support the standard VoiceOVer gestures. But given some quirks with how input is processed when VoiceOver or Zoom is on, using a slingshot wouldn’t be convenient. Messing with that core mechanic would make this another game entirely.

Angry Birds doesn’t have any flashing animations which eliminates the risk of seizures. While video induced seizures are relatively rare[4] most people who suffer from them don’t know they’re susceptible until the first attack. [5]

Conclusion

The WCAG seems like a really good starting point for judging accessibility in games. Not only does it contain the main guidelines above but multiple levels of success criteria to judge how well you’ve implemented a guideline. See Web Content Accessibility Guidelines for the nitty gritty details.

One thing that’s lacking on most platforms is screen reader support. Apple has been ahead of the curve in terms of accessibility and hopefully other platform owners will follow. With the advent of motion gaming being used as a way to entice non-traditional gamers, I’d be disappointed if accessibility isn’t on the minds of Sony, Microsoft and Nintendo.

Its also important to note that ease of usability in Angry Birds goes hand in hand with most of these guidelines. Not only can the guidelines be used as a way to accommodate special needs players, but as a way to judge the usability of your game for everyone.

Notes:

All images of Angry Birds were captured from my iPhone and used under fair use. Cake images taken from Wikimedia Commons.

http://commons.wikimedia.org/wiki/File:Gabe-birthday-part.jpg and

http://commons.wikimedia.org/wiki/File:Cake_from_WHR%28P%29.jpg

Note 1: According to Wikipedia up 10% of American males are red-green color blind. Color blindness is rare amongst women.

Note 2: Austin Seraphin’s account of getting his iPhone

Note 3: For iPhone developer’s Apple’s guide to Accessibility Programming on iOS. The link shows up in Google searches so I’m assuming this doesn’t break iOS NDAs.

Note 4: From the Epilepsy Foundation:

“…the annual incidence of visually provoked seizures in the United States general population is estimated to be one in 91,000. Among young people 7 to 19 years of age – a population that is most susceptible to these provoked seizures and among the most frequent users of video technology – the annual incidence may be five-times as high, or one in 17,500. Only individuals who are susceptible, meaning who are photosensitive, are at risk for developing seizures provoked by light.”

Note 5: Also according to the Epilepsy Foundation(source:gamasutra


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