## 3 Research Methodology
### Materials: Virtual Reality Serious Game  
The virtual reality serious game examined in this article is called ScrumVR and aims to instruct the player in the Scrum framework and some related agile practices in animmersive and effective way. ScrumVR is a first-person game in which the main character is a developer who starts to work in a software company that joins a Scrum team. During the game, the player receives explanations, interacts with other members of the Scrum team, engages actively in the Scrum events, contributes to the development of Scrum artifacts, and employs diverse agile techniques, including MoSCoW and Planning Poker. Screenshots of certain key events taking place throughout the game are shown in Figure 1.  
From a didactic standpoint, the game is narrated linearly, and it is divided into four chapters of approximately the same duration. Completing the four chapters requires the player to spend around 40-45 min. Each chapter is aimed at achieving certain learning objectives in such a way that the player learns how the Scrum framework works. Table 1 presents a summary of the main topics covered by each chapter of ScrumVR. Regarding its technical characteristics, ScrumVR was developed using the Unity game engine and was conceived to be played by using Android devices equipped with a simple \begin{table}
\begin{tabular}{l l} \hline \hline
**Chapter** & **Topics** \\ \hline \hline
1: Introduction & Agile and Scrum foundation. \\  & The role of the Scrum Master. \\  & How to operate a Kanban board. \\ \hline \hline
2: Daily Scrum & Performance of a Daily Meeting in Scrum. \\  & How to select user stories based on their priority and size estimation. \\  & How to interpret a burndown chart. \\ \hline
3: Sprint Review & The role of the Product Owner. \\  & Performance of a Sprint Review. \\  & Retrospective \\  & How to analyze the Sprint performance using a burndown chart. \\ \hline  & Performance of a Sprint Planning. \\  & How to define user stories. \\
4: Sprint Planning & How to prioritize user stories using MoSCoW. \\  & How to estimate the size of user stories using Planning Poker and story points. \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Main topics covered by ScrumVR. Figure 1: (**A**) The Scrum Master explains the foundation of agile methodologies. (**B**) The player chooses a user story. (**C**) The player talks with the Product Owner. (**D**) The player selects a card during a Planning Poker. cardboard. One of the most remarkable points in the development of this educational application is the selected locomotion method. Since ScrumVR was designed for mobile devices, where positional tracking is not available, it was decided to use the on-rails guided locomotion method [53] in order to fully guide the player's movement and minimize the cybersickness feeling. Therefore, the players can look in all directions by rotating the head but do not have the freedom to move wherever they want, thus avoiding distractions and, consequently, facilitating the achievement of the established learning objectives. Additionally, positional sound [54] was used to guide the players to look in the most convenient direction throughout the experience. Another technical feature that was used for guiding the attention of the players was the use of illumination [55]. Another key technical feature of ScrumVR is the use of diegetic menus to allow the player to select an element by looking at it for a certain period of time. Whenever the player can perform an action in the game, a reticle that can be moved by rotating the head is displayed on the screen. When the reticle is placed over a selectable element, it starts to visually indicate the waiting time required to select that element. The diegetic menus used by ScrumVR allow the player to make decisions (see Figure 1C) and engage in agile techniques with other characters by playing mini-games (see Figure 1B,D). These mini-games were developed using a finite state machine model where all possible answers have an associated narrative feedback.