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© ACM, 2006. This is the author’s version of the work. It is posted here by permission of ACM for your personal use. Not for redistribution. The definitive version was published in sandbox ’06: Proceedings of the 2006 ACM SIGGRAPH symposium on Videogames, 1-59593-386-7, July 2006. http://doi.acm.org/10.1145/1183316.1183321
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Abstract Research into improving the accessibility of computer games can enable us to better understand what makes a good gaming experience for all users. We discuss work carried out in developing AudioQuake (an adaption of Quake for blind gamers); specifically the techniques used for rendering information and the nature of this work in contrast to other accessible games (both research and commercial). Based on user feedback regarding the effectiveness of the methods employed in AudioQuake, techniques for not only imparting but allowing vision-impaired users to edit 3D structures are proposed. Taking into account the progress made so far, we make the case for future research work, which could benefit many different types of users and help increase accessibility in other areas such as education. |
Keywords: Accessibility, Audiogames, Multimodal Interfaces, Usability
Categories:
In recent years, a small but thriving “accessible games” market has emerged to provide computer games suitable for disabled (mostly vision-impaired or blind) people. As a result of this the opportunity has been opened up for them to experience some of the more advanced types of computer game technology and enjoyment that sighted gamers have taken for granted for many years.
Academic research into incorporating accessibility and usability principles into games has become popular. Through the work of organisations such as IGDA [16, 25], AudioGames.net [5, 23] and OneSwitch [9], the mainstream games industry is beginning to investigate the feasibility and benefits surrounding accessible gaming.
AudioQuake is the first adaption of an existing mainstream game designed specifically for sighted people that has been made playable by blind gamers. It is unique in terms of the range of Internet-enabled gameplay modes it provides. At one level, it could be termed an “accessibility layer” for Quake1. However, the ethos of the project that surrounds the software is more general—it seeks to:
The task as a whole was split into the following phases of research and development, most of which have been completed at the time of writing.
AudioQuake is a fully-working game that embodies most of our research to date and will be built upon in the future. The AGRIP3 project is a collective name for this and other related work. It employs a Free Software development model, so that users, developers and researchers can easily make use of and collaborate on improving all aspects of the project in future.
Throughout development, the AGRIP project has been shaped by community feedback. This incorporates that given by users via e-mail and using project mailing lists. Many comments from users and suggestions for improvements have been made. Using the mailing list approach has enabled a number of interesting discussions to take place between users of the software, thus giving us a greater insight into how effective the work has been.
Versions of AudioQuake have been demonstrated at Sight Village4 2004 and 2005. They have also been used as the basis of a number of game audio design and game programming workshops at the 2005 International Camp on Communications and Computers5.
Most recently, the core ideas and motivations behind the AGRIP project and how it is contributing to future research were presented at RNIB Techshare6 2005.
The approach taken by this project contrasts with other contemporary research [23, 25, 1] in the following ways.
The rest of this paper expands on the user requirements, design decisions and other issues encountered so far in the final two phases of development described above—specifically rendering techniques that have been developed and accessible 3D structure editing, which is still under active development.
The proposed solutions for both problems are based on our experience and feedback given by users, as well as the methods used in other contemporary research. Therefore this paper is intended to be a comprehensive review of the state of the art, which also describes and attempts to justify our plans for future work.
During the development of the low-level game accessibility infrastructure, the focus was placed on providing the user with the information they needed to perform tasks such as local navigation and general interaction with the game. Techniques for the processing of the structural information that the visual rendering was based on, as well as the filtering and transformation of this information into the most appropriate format for our target audience (blind gamers) were developed (as discussed in [4]).
To demonstrate that these techniques worked, they were coupled with a set of sounds that were created to impart the information that the system deemed appropriate for its users. The initial rendering style, created by using these sounds, is definitely not the only one that could be implemented. This section is a discussion of the main alternatives and their relative merits, based on our work, experience and other contemporary research.
The original rendering style implemented for AudioQuake was based on the idea of “earcons”7. This approach was taken for two main reasons.
The use of principles similar to parallel earcons [6] have contributed to the design of AudioQuake’s earcons.
Three features afforded by the use of well-structured signals have been employed in the game to date:
An example of this is the scheme adopted by the EtherScan RADAR. Earcons that indicate the presence of a creature follow a certain format that is able to inform the player where the creature is vertically in relation to them and if they are aiming directly at it. Different types of creature are represented by distinct timbres; sharper sounds correspond to more capable enemies.
Corner detection, for example, employs an earcon composed of a sound directly in front of the player, followed by another sound to the left, right or both the left and right, depending on which type of corner was found—a left turn, right turn or junction. A similar style of approach was used extensively in the AudioGPS system [15].
The main focus of this rendering scheme was to facilitate fast-paced gameplay, with the hope that after further research it could be used as a basis for allowing blind and sighted players to compete and cooperate.
Feedback from the AGRIP community8 indicates that this style of presenting information facilitates fast-paced gameplay. Most of these users feel comfortable with and enjoy this style (see section 4 for details). A few players have utilised the consistency it provides to become highly skilled at navigation and aiming. This is very similar to a trend seen in sighted gamers: the most skilled players9 often purposefully lower the graphical detail levels of their games so as to remove the noise caused by random graphical effects and allow them to concentrate on the gameplay.
An opposing scheme to the one already implemented and described above is a rendering scheme based entirely around intuitive real-world mappings and effects. This scheme would make use of auditory icons [17] and technologies such as 3D sound and effects. The main characteristics of such a scheme would be as follows.
There have been requests for such an approach to be implemented from the AGRIP user community. It would certainly make AudioQuake “feel” more like other popular accessible/audio-games [10, 25]—though, we expect, at the loss of at least some of the speed and accuracy afforded by the symbolic rendering style. This is suggested as an area for future research.
The above two rendering scenarios may be seen as opposing ends of a linear spectrum—one scheme promoting fast-paced gameplay based on explicit signals and the other promoting better immersion through the use of implicit cues. It could be imagined that some forms of hybrid rendering style may exist between them. Due to the varying nature of users’ requirements and the conditions in which they may interact with the system10, it could be beneficial to allow them to specify a scheme that is more suited to them, rather than forcing them to one of the extremes discussed above. A taxonomy of styles that could be used to build up such a hybrid scheme is given in figure 1.
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Some proposed techniques (from existing literature and ideas generated within the AGRIP project) for allowing this are as follows.
An example of how intelligent style selection could be used follows: If the user is battling a group of enemies in a game, they need more accurate positional information about the enemies. Such information may be presented in preference to less important navigational cues, according to the principles developed to ensure effective usage of the (limited) bandwidth between the computer system and the user.
The system would choose the most appropriate rendering style based on guidelines such as those described below.
So far, adaptions targeted at blind users in particular have been discussed. However, once the processing of information has been decoupled from rendering, we are able to utilise many other different rendering styles to suit users with other needs.
The next logical step for AudioQuake is to better support vision-impaired gamers through the use of sprites and high-contrast colour schemes (as have been used in Terraformers [25], as well as many GUI Desktop Environments). This could easily be achieved as all of the required information is already available to the rendering system.
This brings us to the possibility of supporting non-disabled users better than they currently are. It has been asserted that there are similarities between designing interfaces for normal users in unusual environments and designing interfaces for users with unusual requirements in normal environments [19]. This implies that the techniques developed here and as part of other research projects may be of use for users of mainstream applications on devices such as PDAs and cellular telephones.
Further to this, it has also been asserted that a large percentage of adult computer users would benefit from some type of adaption to their needs in the systems they use [11]. On a similar note, websites are on average 35% easier to use for everyone if they comply with accessibility standards [8]—in fact, the W3C’s Web-Content Accessibility Guidelines borrow heavily from establised usability principles [24].
We submit that such an adaptive rendering system would be useful for many gamers. The popularity of the “Doom 3 Closed Caption” modification—and the subsequent inclusion of closed captioning in mainstream games by other developers—also supports this [12].
Further research may also reveal guidelines (similar to those already established in the areas of Human Interfaces and Web Usability) that could provide heuristics for design decisions (such as how many of the different rendering styles proposed in figure 1 should generally be applied at once, both to different objects/events and the whole scene).
The benefits of having multiple rendering “layers” extend further than being able to support users with varying requirements. It has been asserted that well-designed multimodal interfaces can provide some error-correction, at least for certain tasks [22]. Additionally, providing reinforcement for the primary means of rendering can both aid cognition [20] and increase the user’s enjoyment of the experience [23].
As 3D environments are used more often in our society, for work and leisure, there are numerous opportunities to include disabled people in them. Such opportunities include games; Collaborative Virtual Environments (CVEs); public information services11 and possibly even modern art.
The techniques presented and cited in this paper go much of the way to affording people with sight loss access to 3D environments. Since our current work has made these techniques applicable to contemporary 3D engines, it is hoped that they will be adopted and improved by others. One major hurdle that remains, however, is to allow blind people to create 3D environments.
The common technique for 3D modelling/level editing software is to allow the user to construct and modify parts of the world via a GUI that features a real-time preview of their creation so that they can receive feedback on changes quickly. This is, of course, inaccessible to certain groups of people.
A preliminary architecture and some of the low-level components of an adaptable level description system have been developed, based on our experience with other areas of the project. This architecture is presented in figure 2 and its benefits, for all users, described below.
The design applies the the same principles used in AudioQuake to improve the accessibility of constructing 3D structures for both disabled and non-disabled people:
As indicated in the diagram above, a similar approach could also be applied to related aspects of 3D applications such as in-game cinematic sequences. This could well be achieved in an integrated manner by including other namespaces into the XML-based standard for defining structures (such a technique is used by the DocBook standard to incorporate SVG and MathML into DocBook documents, for example). So far the lower levels of the level description system have been developed and research is ongoing.
It should be borne in mind that we do not expect to give blind people an in-depth understanding of lighting and texturing issues—primarily we’re discussing the definition of structure alone. However, this layered approach allows for the use of semi-automated approaches to deal with the problems these issues pose. One approach is to use the idea of styles/stylesheets to apply pre-defined texture or lighting themes to a map. In a collaborative environment, the layered approach can be used to separate the definition of structure from appearance and sighted assistance can be brought in to apply textures and lights to the structure.
As with many aspects of the AGRIP project’s work (and the views expressed in literature this review cites), the goal is to produce results that can be applied in areas additional to games. It is clear that the above system may be of use for editing and verifying 3D structures which may be used in other systems than games. However, there are other potential uses of the work.
Increasingly, visualisations and Collaborative Virtual Environments (CVEs) are beginning to be used in the workplace as well as computer games at home. It is our opinion that we should concentrate considerable effort on making these technologies accessible to as many people as we possibly can before they become mainstream—currently adoption in the workplace is slow, partly due to issues involving the average work environment [7], as well as the difficulty of navigation [27] (another area in which accessible gaming research may make contributions).
Members of the AGRIP mailing list and wider accessible gaming community, who have played AudioQuake before, were invited to answer a short web-based questionnaire. The survey was designed to ascertain users’ opinions of the game and project as a whole, in order to gauge the project’s success and reception of our future development plans. Figure 3 shows the results collected in the relevant part of the survey; 20 users took part. The full text of the questions asked is given in Table 1.
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From examining the data collected, we can draw some conclusions.
Due to the audio-centric nature of the game, selected comments from the users are included in figure 4, to give the reader an impression of the gameplay experience and a qualitative idea of how the project has been received.
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“I think the ESR needs to more accurately and swiftly reflect the player’s position and what’s around them, especially enemy targets. I find there is a lag between position change and new feedback data, such that often, even though I hear that an enemy is within range, the enemy is not in fact. I’d also love to see more done with 3-D audio mapping of terrain. A GREAT job has been done overall, and I wholeheartedly encourage continued development of this application and its myriad uses.” –User 1 “Audio Quake is the only game I play regularly any more. I’ve played it the most out of all the games I’ve played and purchased.” –User 2 “We really need a map editor. Some standard maps can be used by AG users, but especially for new users, we need to be able to create maps with lots of right angles and grid-like layouts. For the experienced players, the game loses novelty with out new areas to play. New areas/maps cause experienced users to come up with new strategies.” –User 3 “Why are you working with the first game of Quake?” –User 7 “I would like to see Audio quake utilize controllers that have force feedback capabilities. Being able to detect or identify objects within the game using touch and feel would be great and in some respects better than sound identification. Right now, there are so many sounds and noises within the game that it’s become distracting. I think utilizing some sort of voice command system might be interesting also. ...” –User 20
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This review of the current progress of the AGRIP project and how it fits in with (and differs from) other research has left a lot of questions open fur subsequent research to answer. Some of the main areas we hope to focus on in the future are outlined below.
Further issues that are being researched currently but are out of the scope of this paper are: local navigation (part of the low-level game accessibility issues); improving real-world mobility and spatial awareness; accessible interaction and collaboration between players and teaching blind students programming concepts using systems based on game technology.
Research into the potential usefulness of game-like technology for education is gathering momentum [18, 13]. It is important that any future developments in this area promote inclusion for all users. The use of high technology doesn’t guarantee a usable experience for everyone (as the web has shown us [8]) but the use of technology such as that behind AudioQuake could help in a number of ways.
These are also areas for future work, but are suggestions aimed at the wider community. The output of the AGRIP project is, to our knowledge, the only accessible 3D application development platform that is licenced as Free Software and is aimed at providing people from such varied domains with a way to further accessibility in those areas.
This work shows that even some of the most time-critical and competitive mainstream computer games can be made accessible to people with vision impairments and sight loss. The techniques developed for ensuring the rendering of the gameworld caters to the needs of the user are performing well, but there is still significant scope for improving those techniques; making them applicable to users with other disabilities—including those without disabilities—and using them in other applications, such as 3D structure overview and editing.
We have discussed how the development of AudioQuake builds on, but also contrasts with existing research in this area. We have also proposed, based on past experience and user feedback, a number of new areas in which the techniques developed could be used.
We would like to thank the community that has evolved around the AGRIP project for its continued support and constructive criticism—special thanks go to those in both our and the wider accessible gaming communities who took part in the survey. This project would not have been possible without the release of engine technology to the community by id Software, the help of the Quake and QuakeWorld community (including members of QuakeSrc.org, ZQuake and QuakeForge), or the sponsorship of the Grundy Educational Trust. Thanks to Loughborough University for endorsing this project and allowing the results to be disseminated Freely.
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1the seminal first-person shooter from id Software, released in 1996
2We also aim to make as many features as possible rely only on mainstream hardware, so as to keep barriers to entry at a minimum.
3Accessible Gaming Rendering Independence Possible (hence the acronym!); http://www.agrip.org.uk
4http://www.qacsightvillage.org.uk/
5for vision-impaired people; http://www.icc-camp.info/
6http://www.rnib.org.uk/techshare/
7Structured sounds, often obeying musical conventions, that are designed to alert the user to an object or event. They do not “sound like” their referents.
8the core group of users of our software, who give feedback and make suggestions via a mailing list
9those who are able to make money from gaming
10via visual, auditory or haptic interfaces, with certain different types of sensory preferences or impairments, for example
11such as the Virtual International Space Station, which was created using the Unreal (game) Engine.
12Such as violation of building standards, the creation of difficult-to-navigate floor-plans and so on.
13This complements current game design techniques such as open-ended character development and could well serve to increase replay value.
14This is the same way that cross-platform, cross-language compilers such as GCC work—by having front and back ends target a common intermediate language.
