###### Abstract  
This paper proposes a novel approach to audio game design by introducing the concept of speech puzzles (spuzzles) to describe the utilisation of recorded voice for the creation of audio puzzles in ways that challenge players' different listening modes. In the fields of audio games and audio-interactive applications, speech serves instructive, descriptive, narrative, and in some cases--in the form of hints or quizzes--gameplay purposes by addressing users through language. The suggested approach of spuzzles extends this potential by including, besides encoded meaning, the acoustic properties of sound, thus engaging the user's causal and reduced listening modes in parallel with the semantic listening mode. An audio game consisting of four inherently different spuzzles was designed as proof of concept and tested by seven third-year students of Audivisual Arts, who elaborated on their experience through a focus group semi-structured discussion. Despite their difficulty, the spuzzles were well accepted by most of the participants (5/7), whereas all participants agreed on their acoustic richness, need for concentration, and independence from pre-existing musical knowledge. Therefore, the authors suggest that the proposed design approach could serve as a paradigm for future research in the design of complex audio-based game mechanics. audio games; puzzles; audio puzzles; game design; puzzle design; listening modes +
Footnote †: journal: Medical  
blind users have been criticised as being too simple [6]. On the other hand, by adding complexity to the audio representation of the game's facets, it becomes too difficult for sighted players who have not developed their listening skills sufficiently to accomplish the game's tasks without visual support [7]. Making the game not just accessible but truly inclusive, i.e., an experience as similar as possible for sighted and visually impaired players, requires a careful design of the sonification strategy from the start of the development process [8]. Last, the design of additional layers of audio information to create interactive immersive environments must fulfil the needs of both functionality and aesthetics [9]. In other words, the acoustic experience must not only serve the game's mechanics but also be artistically appealing. This research aims to contribute to AG design research by investigating a new design approach for AG mechanics proposed by the authors, which employs the acoustic properties of speech for shaping puzzles that challenge players' different listening modes. As proof of concept, the game \"Break the Audio Code\" was designed to demonstrate different facets of this \"spuzzles\" (speech + puzzles) approach, from using unprocessed speech recordings to complementing them with background sounds, and from applying simple editing actions to heavily manipulating the recordings via audio effects, in order to engage players' semantic, causal, and reduced listening. The acceptance of spuzzles was evaluated in a playtesting session and a consequent semi-structured discussion by a focus group comprised of seven students of the Audiosvisual Arts Department of the Ionian University in Greece. The authors are aware of the limitations of their research, since the number of the participants is small, their profile similar, and no quantitative data were analysed. In this research, a qualitative research approach was employed aiming to provide preliminary insights regarding the perception of spuzzles that could serve as the basis for their future systematic design and utilisation. Since spuzzles employ different listening modes and thus exercise players' listening skills, they could be used to address the aforementioned challenge that sighted players are failing to cope with complex AG mechanics (Figure 1). The rest of the paper is structured as follows. Section 2 presents the theoretical framework of this research focusing on its two main axes, (a) puzzles and (b) speech, in AG  
Figure 1: Research scope. design.