## 3 Game Design  
This section analyses the design of the four spuzzles of the AG \"Break the Audio Code\" designed by the authors for the purpose of this research. The content of the game was sought in the typography collection of the Ionian University Museum in Corfu, Greece. The collection is situated at the Ionian University Department of Archives, Library Science, and Museology, and exhibits machines, tools, and objects related to various phases of the production of printed or typed archival material. More specifically, the exhibits fall under the categories: (i) typesetting, (ii) printing, (iii) bookbinding, and (iv) typing. One exhibit was selected from each of those categories, and a descriptive text was provided by the museum for each of the selected exhibits. The texts were narrated and recorded by the corresponding author (male voice), and these recordings served as raw material for the creation of four respective spuzzles (Figure 2). There were three major specifications in the design of the spuzzles:  
1. In terms of mechanics, they had to engage players' different listening modes: semantic, causal, and reduced. 2. They also had to highlight important aspects of the represented exhibit. This meant that conceptual connections had to be established between selected information and its sonic representation. 3. The audio outcome had to be clear to the listeners, providing all the necessary clues to solve the puzzle. In consideration of the above, all recordings were first processed through \"noise reduction\" and \"compression\" effects, which removed any unwanted background ambience and increased the volume of the remaining voice. For the design of the audio puzzle, the methodology previously proposed by the authors was followed, according to which a thorough research and analysis of the information to be sonified leads to designing the game's genre, levels, and mechanics [45]. The authors relied on two axes of description for each of the exhibit: (a) the item's purpose and historical importance in terms of the general category that it belongs to (typing, bookbinding, printing, typesetting), and (b) the item's specific information in the narrated text. It was decided that the solution of each puzzle be a two-digit number (10-99), as it is an easily manageable piece of information. Establishing semantic connections between sound and exhibit was quite simple since the source of information consisted of spoken language. The causal and reduced connections proved to be more complicated to forge, as elements of the item itself and the function it serves essentially had to be symbolically represented by audio properties and processes. Any audio effects used for this purpose should be unambiguous and avoid causing cognitive overload. From this perspective, the authors felt that their role as designers were reminiscent of that of a neurosurgeon, who performs a delicate operation. The design of each spuzzle is analysed below:  
**Spuzzle 01. \"Typesetting\"--targeted listening mode: Semantic**  
The exhibit that was selected for this puzzle is a large piece of furniture with typographic cases with the following text narrated and recorded:  
_Within a printing house, each typeface had a family of letters (font), in all even sizes (from 6 to 72). The smaller drawers contained from the middle upwards Latin characters and from the middle downwards their respective punctuation marks._  
The authors' intention was to highlight the main function of this exhibit, which is to store the letters and all other symbols for the typesetting process. Thus, the authors attempted to draw players' attention to one basic property of these characters, namely their size. The semantic approach was selected for turning these words into a puzzle. Players need to listen carefully and think about how many different font sizes are stored in the exhibit. Since only even sizes are mentioned, including both 6 and 72, the \"solution formula\" is \((72-6)/2+1\), which results in 34. Figure 2: Game content. **Spuzzle 02.