# Emotion-Driven Music and IoT Devices for Collaborative Exer-Games
## 2 Related Work
### Music and Exer-Games  
Music has always played a significant role in sports as a motivational tool [1; 15]. This importance is directly related to the emotions that music can evoke in listeners during physical activity. In the context of exer-games, several studies have explored the positive effects of music on players [6; 16], concluding that music increases participants' motivation, reduces the perceived exertion during exercise, and adds value to the activity. As a result of these benefits, music also improves player adherence and engagement in physical exercise. This long-term participation is particularly valuable in games designed for medical rehabilitation or the treatment of disorders [11; 17; 18]. Despite these advantages, the use of music is not always optimized to enhance the player's experience or the effectiveness of physical interventions. In various studies, players have expressed the need for personalized strategies that maximize the benefits of music during gameplay [5; 9]. These strategies can be based on listeners' musical tastes [19] or on their achievements over the course of the game [20]. The latter could more effectively combine the logic of the game and the individual tastes of each player. Unfortunately, many exer-games are primarily designed for specific demographic groups (such as commercial games targeting younger audiences), and often use music that is less suitable for other populations, such as older adults [18]. This mismatch can lead to players losing interest in the game and discontinuing participation early [6; 9]. Dancing games were among the first applications to integrate music with physical activity. The advent of virtual reality has enabled a new generation of these games, offering players a different dancing experience [21]. These experiences can be single- or multi-player. Single-player games are mainly designed for entertainment and fitness training, while multi-player games focus on social interaction and improving dancing skills [22]. In all these applications, music is a key gaming element, selected according to the goals of each activity. Some of the most popular commercial dancing games include Dance Dance Revolution, Just Dance, Eye Toy Groove, and Beat Saber [23]. The first two games score the player's ability to move in rhythm with the music, with different songs played according to the difficulty of each level. These games also support multi-player experiences, where players compete without directly interacting for the best score. In the latter two games, players attempt to hit oncoming objects in sync with the music. The level of physical effort required during gameplay is influenced by the song being played. Additionally, these games include a multi-player mode based on challenges, where one player selects a song and challenges others to achieve the best score. Music is also used as an ambient element in the design of games. The selected music tracks or song excerpts are chosen based on the type of exercises to be completed, the difficulty level and pace of the exercises, or the remaining time for completion, among other criteria. The primary goal is to motivate and guide players toward achieving their milestones [24]. Music can also serve as background for the narrative that ties together the different exercises in a game [25]. The use of narrative to connect exercises is an engagement strategy aimed at increasing the effectiveness of exer-games. In these cases,game developers typically select the same ambient music for all players. This selection is usually based on the acoustic characteristics of the music and aims to elicit specific emotions in participants (such as relaxation, stress, or happiness). Acoustic characteristics, particularly rhythm, tempo, and beats, have been shown to be highly effective in controlling exercise timing and enhancing player performance [26; 27; 28]. Musical rhythm has been explicitly used in the design of some exercise-based games, particularly in the health and well-being fields.