Playing Audio-only Games: A compendium of interacting with virtual, auditory Worlds

When thinking about playing computer games, most people envision young persons addictively enjoying audiovisual games like Quake, Doom or Counter Strike. The commonality in these games is that the majority of information is provided visually. The interaction with such virtual environments is, with slight modifications, straightforwardly derived from our real world actions and own experiences. Opposed to these games, a small niche of audio-only computer games has evolved. These games are often developed by and for the visually impaired community, but can also be played by sighted users. The advantage, as well as the challenge, is that these games can only be played trough sound. Every game related information is sonified acoustically and several techniques have been developed to aid in the navigation, orientation and interaction with the virtual, auditory world. Several games can be found and a nice collection is compiled on the audiogames.net website. Our work, as well as this paper, are motivated by our current research in this area and the development of an audio-game framework. This framework not only allows the development and play of audio-only games, using several intuitive methods for sonification and interaction, but also includes an authoring environment and a simple story engine. The foundations are laid out, and we are currently working on the development of several games to exemplify the results. One of the main benefits of audio-only games is their excellent suitability for mobile gaming, as no visual information and hence, no screens are necessary. This allows to even play these games with the attention distracted to other activities. Technologically, audio-only games are relatively easy to build and, besides some additional hardware, which would allow a deeper immersion into the virtual environment, the equipment needed is simple, affordable and small in size. Another advantage is a, similar to reading books or listening to audiobooks, increased level of immersion with a much higher stimulation of the participants phantasy apposed to visual gaming. This results from the lack of information that is presented and causes the player to imagine the missing pieces and to "shape" the virtual environment through own experiences. For story based game genres, one could envision audio-only games as the unification of entertaining computer games and audiobooks. So far, several genres for playing audio-only games have been developed. The most suitable ones are strong content and story based games, like adventures and puzzle games, but the concept of audio gaming can also be applied to certain action style games. Examples include adventures like "Der Tag wird zur Nacht" and "Terraformers" and action games as "Audio Formula 1" and "Drive". One of the very interesting aspects is, that audio games, as they are not only played, but also perceived in a different manner, may offer a complete new type of game genre. Audio-only games are more focused on auditory cues and perception. By combining this with alternative techniques of interaction, suited to auditory environments, new ways of interfering with virtual worlds and stories can be explored. The convenience that no visual information is necessary for the play of these game, is on the other side also the biggest challenge. Most of our environmental information is acquired through visual perception. On the contrary, our ears often tell us where to search for it, if we move our head into the direction of the sounds origin. One of the largest drawbacks of auditory displays is their insufficiency of being able to provide a general and simple overview of a scene like a picture. Therefore, we have to employ additional techniques, that are able to deliver this extra information in a different manner. In our framework we employ several methods to compensate for this deficiency. These techniques allow for an easier navigation and orientation within these virtual, auditory worlds. In our work, we will give a complete overview of playing audio-only games, ranging from techniques for actually playing these games, to methods to author and design auditory environments. We also provide details about the diversity of audio-visual perception and discuss which genres are most suitable for playing audio-only games. The final paper will consist of mainly three sections: The first is an introduction to audio-only gaming and games and will motivate for the development, as well as for the play of such games. Here, we focus particularly on the benefits of audio games and existing work. The second section analyzes audio-only games and has a closer look on available game genres and the structure and design of audio-only games. As these games tend to be strong story dependant, this section will also include a paragraph on storytelling for audio-only games, mainly centered around auditory adventure games. The last section examines the techniques which are used to actually play such games. This covers a very brief review of 3D sound and room acoustics and is mostly centered around sonification and interaction techniques that support navigation, orientation and object interaction. In this section, we will also discuss details regarding the modelling, the design and the authoring of auditory environments and audio-only games. The paper will conclude with the presentation of a framework, that is currently developed along this project, and which can be used to create, author and play audio-only games. More information can be found on our website at isgwww.cs.uni-magdeburg.de/games/audio.