Data acquired from Phase I in this study resulted in an app named Haddy, which means “calm down” or “relax” in the Arabic Emirati dialect. In this phase, experts were involved in evaluating the usability of the final version of the app. In order to participate in this evaluation, an expert needed to have at least 3 years of experience in usability testing and software engineering. The research team used personal contacts to recruit 5 experts for this study. For the heuristic evaluation, 5 participants were considered a sufficient sample size [28].

Experts were required to download the app from the Google Play Store to evaluate the app. The evaluation was conducted using a questionnaire with a total of 30 items, 19 of which were based on Nielsen’s usability heuristics. Match between system and the real world, visibility of system status, memory, minimalist design, error prevention, consistency, user control, and flexibility are among the heuristics used in this evaluation. A 5-point Likert scale was used for the assessment (1=strongly disagree, 2=disagree, 3=neutral, 4=agree, 5=strongly agree). In addition, 9 items were included to score each feature of the app on a scale from 1 to 5, and 2 open questions were used to highlight the app’s advantages and problems related to the usability of the interface design.

Ethical approval for the study was obtained from the relevant authorities at the United Arab Emirates University (ERS_2020_6156).

The final version of the app (Figure 4) has the following key features: (1) biofeedback-based game, (2) card game, (3) falcon game, (4) memory game, (5) breathing exercise, (6) yoga videos, (7) positive messaging, and (8) mood tracking calendar. Since it is directed at people in the UAE, the app uses both Arabic and English languages.

The biofeedback game (Figure 5) was designed to help the player gain control over physical symptoms of anxiety. It requires the use of a smartwatch for heart rate tracking. To start the game, the player must first connect to the smartwatch by tapping the connect button. Prior to that, the user must put on the smartwatch and pair it with the phone via Bluetooth. After a few seconds of connection, the heart rate should appear. Heart rate is represented by colored circles: green (normal, at rest), red (high, anxious), and blue (low, dangerous). The normal heart rate falls between 60 and 100 beats per minute according to MHPs. When the color is not green, the player must relax by practicing activities such as breathing until the color goes back to green.

The card game (Figure 6A) is a classic mini-game with the goal of turning 2 matching cards at the same time. This game was designed to divert the user’s attention away from anxious thoughts. The game consists of three difficulty levels: easy (4×4 grid), medium (5×4 grid), and difficult (6×4 grid). The graphics on the cards portray animal species from the UAE, with a desert in the background. The game has no time or movement restrictions and it ends when all of the cards are acquired.

The falcon game (Figure 6B) is a side-view perspective arcade game used to divert someone’s attention away from negative thoughts and toward adjusting the falcon’s position. In this game, the falcon must fly through deadly drones to win. To keep the falcon flying, the player must keep pressing on the screen. Every 10 seconds, the score increases. If the falcon hits a drone, the game will end. If it does not, the game will continue, with the falcon’s speed increasing as the game proceeds. The highest score of the player will be saved.

The memory game (Figure 6C) is another game offered by the app, with a similar principle to the card game. A set of Arabic coffee cups is presented, and a sequence of pouring coffee into each cup begins one by one. The player must memorize and match the sequence in order to win the game. If the player chooses the incorrect order, the game will end. This game also presents three difficulty levels: easy (4-item sequence), medium (6-item sequence), and difficult (8-item sequence).

The breathing exercise (Figure 7A) is a guided breathing exercise that instructs the user on when to inhale and exhale. Users are able to customize the duration of the exercise. They have four options: 2 minutes (which is the shortest), 5 minutes, 10 minutes, and 15 minutes (the longest). We added relaxing music to the breathing exercise based on feedback from the MHPs.

Yoga videos (Figure 7B) were included in both English and Arabic. There are a total of 12 yoga videos available, half in Arabic and half in English. The videos were obtained from YouTube channels; hence, they can only be viewed with internet access.

Positive messaging or quotes (Figure 4) were placed at the bottom of the homepage screen. Some of the quotes come from well-known Emirati public figures, such as the UAE’s beloved first president, Sheikh Zayed bin Sultan. When the user reopens the app, a new quote will appear.

A mood tracking calendar (Figure 7C) is a simple feature for people who wish to keep track of their mood on a daily basis. This can be useful when reflecting back on how one has been feeling over a period of time. Different moods can be observed if the user slides the progress bar. Users can define their current mood by selecting 1 of the 9 moods (tired, lonely, bored, stressed, I don’t know, calm, happy, excited, and wonderful) indicated with an icon and text. The user can add different moods in a single day by clicking the “Add mood” button. The moods will appear in chronological order in a weekly calendar.

All 5 experts completed the usability evaluation questionnaire for the final version of Haddy. Table 1 shows the mean usability score from the experts’ point of view, with the consistency of the app scoring the highest. On the other hand, the ability to hide or display information, which is an aspect of minimalist design, was clearly low. In addition, both items of flexibility, including customization of functionalities and properties of interfaces, scored less than 4.

According to the experts’ evaluation, the positive messaging and the card game were the most well-designed features of the app. Biofeedback, the falcon game, and the yoga videos, in contrast, had the lowest scores of all the features, but their scores remained over 4. Overall, the app design scored 4 out of 5. Table 2 shows the rest of the findings.

The last two questions in the usability questionnaire were designed to learn what experts liked and did not like about the app design. All the experts agreed that the app is simple and easy to use. One expert pointed out that the design suits the Arab region. On the other hand, experts identified some disadvantages, such as the amount of text displayed at once, improper error handling, and inconsistency with the display of icons. Along with the feedback, suggestions on how to improve the current version of the app were acquired and presented in Table 3.

The goal of this study was to develop and test the usability of a biofeedback-based app with serious games for anxiety management for young adults in the UAE. According to the results of the questionnaire, games with heart rate tracking and breathing exercises have the potential to increase young adults’ interest in gaming as a stress-relieving method. This app was co-designed with MHPs in order to ensure the content’s integrity. The involvement of MHPs in the design process is thought to improve the efficacy of apps and to boost users’ trust in apps. A study has shown that the number of installs of anxiety apps that included MHPs was significantly higher than the number of installs of anxiety apps that did not include MHPs [29]. The target population for this app was young adults with mild to moderate anxiety symptoms, and not those with severe anxiety, since according to the MHPs involved in this study, those with severe anxiety were less likely to use this method of “self-help.” This is supported by findings by Christensen et al [30] that people with high anxiety symptoms were more likely to drop out of internet-based therapies. MHPs considered games as an effective technique to boost user concentration and shift attention away from anxious thoughts, resulting in better anxiety reduction outcomes. Additionally, audio was incorporated into the breathing exercise because sensory experiences such as music were emphasized for relaxation and reduction of anxiety [31,32].

Good usability ratings and positive feedback from experts may be in part due to the elicitation techniques used in Phase I, which included obtaining information from potential users, existing solutions, and MHPs. Experts recommended increasing customization, both for the interface and for particular features. Many users of anxiety and other mental health apps place more emphasis on customization [33]. Experts were generally satisfied with the app and found it easy to use, with only minor flaws that will be addressed in the next version. The findings of this study resulted in a future modification to facilitate the process of testing the app in young adults with anxiety.

We believe that our study will provide developers and practitioners insight into potential and acceptable content and features, as well as different considerations while developing an app for young adults with anxiety in the UAE. Based on the findings, we recommend app developers to consider (1) the involvement of users and MHPs in the requirement elicitation process to improve usability; (2) reducing the amount of information presented in the user interface; (3) customization of the user interface as well as some elements of proposed features; and (4) handling all errors that may arise and ensuring the user is aware of them.

This study has a few limitations. The first limitation is that the usability of the high-fidelity prototype was evaluated by experts rather than young adults with anxiety; however, these results remain important, as the experts’ feedback will ensure that the app is suitable for use with the target population. Another limitation is that this study focused on the app’s interface conviviality, not the efficacy of the app in reducing anxiety symptoms, as this would require participant recruitment. We hope to overcome these limitations in future work by conducting a usability and efficacy evaluation with young adults with anxiety in the UAE. Finally, this app was initially developed for Android, but we intend to expand it to iOS in the future.

This study has resulted in the development of a culturally sensitive biofeedback-based app with serious games to help young adults with anxiety in the UAE. Haddy was developed in collaboration with MHPs and tested by experts. The app has been well received by MHPs, with positive feedback about its ability to help with anxiety management. Experts who have evaluated the use of the app reported that it is simple and easy to use. Experts’ feedback will be included in the next version of the app. We intend to conduct a study to investigate the usability and impact of the future version of the app on a sample of young adults with anxiety in the UAE.