The name KIJANI is Swahili and translates to “green.” It stands as a German abbreviation for “Children & Youth: active, nature-conscious, innovative!” KIJANI is a smartphone app explicitly developed for children and adolescents to increase PA through a gamified approach. The basic game concept is that virtual coins can be “earned” through PA, for example, in the form of a collected step count. These coins can in turn be used to “buy” blocks, which can be used to create virtual buildings and integrate them into the player’s real-world environment via augmented reality, see Figure 1. Using challenge-achievement-reward loops as provided via the coin reward system in KIJANI was shown to increase the desire to play in previous research [14]. PA of users is detected via accelerometers integrated into smartphones and is linked to the KIJANI app on a technical basis.

Earning coins is based on a fitness challenge in the app, for example, consisting of 10,000 steps per day. The achievement of the main goal as well as intermediate goals are rewarded with coins. The main goal of 10,000 steps is rewarded with 50 coins, and intermediate goals, for example, 5000 steps, are rewarded with 20 coins. The blocks differ in price, for example, grass and brick cost 2 coins, water and bookshelf cost 5 coins, and the most expensive is glass and gold with 10 coins. Some blocks such as dirt and stone are free and unlimited to ensure enjoyment for the users. A progress bar in the app shows the individual progress over the course of the day, encouraging participants to reach the daily goal.

KIJANI is designed to be played both alone and with friends in a group. To play together with friends, requests must be sent and confirmed. Then KIJANI can be played together in a group and buildings can be created together. Players can individually specify who can visit, build, and administrate buildings, which ensures that no uninvited players can participate and therefore is another safety issue in KIJANI. In addition, the individual activity behavior can be compared with friends in a ranking list, which is another incentive for PA, see Figure 2. The ranking is also available for nonfriends, as there is a setting to show all players.

KIJANI was developed in cooperation with the research project “WALKI-MUC – Evaluation of physical activity opportunities and walkability perceived by children and youth in Munich,” conducted by the Associate Professorship of Didactics in Sport and Health at the Technical University of Munich. In WALKI-MUC, children and adolescents aged 6 to 17 years (n=93) identified walkable places in Munich (places within walking distance from their homes) that they considered supportive of PA. The participants provided qualitative descriptions of these PA-friendly places through participatory methods such as photovoice, walking interviews, and mapping exercises while researchers tracked the walked routes and GPS locations. Focus group discussions and the one-on-one sharing of the individual significance of these places in interviews provided insights into factors contributing to safety and attractiveness (eg, accessibility and presence of people) at the locations, as perceived by the children and adolescents. The descriptions and locations of these identified PA-friendly places of WALKI-MUC are incorporated into the KIJANI app. KIJANI can only be played in these comprehensively defined, child-friendly locations, ensuring that KIJANI can only be used in a safe and appealing environment for the target group. There is a location search feature implemented in the KIJANI app to find the play locations in the close environment. In addition, the route to the locations is displayed on the map (see Figure 3). This not only encourages users to be active but also supports a healthy lifestyle as extra steps can be accumulated.

At these play locations, a server is created in which KIJANI is played. Multiple servers can be created at 1 play location so that different buildings with different friends can be created at 1 play location. If players want to play in groups, friends have to be invited to the server to ensure that the players are in a safe play environment where no one else can intrude.

It is planned to evaluate the KIJANI app in a 2-phase approach as displayed in Figure 4. The phase-I evaluation will be a mixed methods design, in which the target group evaluates the user experience of the KIJANI app. The phase-II evaluation will be a 2-arm randomized controlled trial (RCT), in which the intervention group (IG) will use the KIJANI app, while the control group (CG) will not use the KIJANI app. Within this second evaluation stage, the effectiveness of KIJANI will be assessed via objectively assessed PA as well as standardized questionnaires.

The study protocol has already been approved by the ethical board of the Technical University of Munich (project 2023-185-S-NP). All children and their guardians will provide written informed consent.

For the described evaluation study of KIJANI, a development version of the app is used and distributed through TestFlight. Participants are required to log into the app using pseudonyms to safeguard their data privacy. Throughout app use, step count and GPS location are shared and digitally stored in a firebase. Personal data is processed in accordance with the provisions of the current data protection laws pursuant to Art. 12 (1) BayDSG. Prior to the official release of KIJANI, all necessary international regulations will be considered.

Children and adolescents at the age of 10-16 years will be included in this study. Children with walking impairments and cognitive impairments that hinder their ability to understand the task will be excluded from the study.

The data analysis will involve both descriptive and analytical analyses. Initially, descriptive analysis will focus on the sociodemographic characteristics of the study population. Normal distribution of the data will be tested with the Shapiro-Wilk test. In terms of dropouts, intention-to-treat analysis will be performed using multiple imputations, to be able to calculate with a complete data set. To capture the longitudinal development of the activity level throughout the study period, a linear mixed model will be used to compare the change of the PA behavior over time between IG and CG. To investigate differences between the groups in activity-related self-efficacy, health-related quality of life, and PA enjoyment, these will be compared with 2-tailed t test or Mann-Whitney U test as appropriate depending on the distribution of the data. All analyses will be performed with RStudio (version 4.1.2; RStudio Team), with the level of significance set to 2-sided P values <.05 for all tests. RStudio was used for its tailored integration with the R programming language, providing an efficient and organized environment for reproducible data analysis, visualization, and documentation in our scientific study.

KIJANI is a mobile game explicitly developed for PA promotion in children and adolescents with a special focus on creativity as well as PA in the outdoor setting. The objective of the KIJANI intervention is to increase everyday PA in adolescents through a digital intervention approach using gamification and augmented reality. This study protocol describes the KIJANI intervention in detail, as well as the evaluation approach.

Even though activity promotion is highly indicated in adolescents, this young target group is difficult to reach, and adherence to intervention approaches, especially over the long term, is mostly rather low [22].

Several previous studies have assessed the effectiveness of mobile health approaches to increase PA in healthy adolescents. A systematic review on the effects of mobile health to increase PA concluded that mobile devices and apps may be an effective strategy for promoting PA in adolescents as they have high technology use. However, overall, there is only a small number of studies; a lack of RCTs; and a high risk of bias in this research sector, mostly including self-reported measures with the risk for recall as well as report bias [23]. Another systematic review on the quality and features of apps to improve PA, sedentary behavior, and diet also reported that generally, very few apps are available that specifically target children and adolescents and app quality was only moderate [24]. Overall, there is a need for high-quality app-based activity promotion approaches especially in children and adolescents.

Some previous studies have assessed the effects of digital gamification approaches on activity promotion. A meta-analysis revealed that the popular mobile augmented reality game “Pokémon Go” was associated with a significant increase in the users’ daily step count. In the game, participants are required to travel to different locations to capture virtual characters. Even though the game was not primarily designed to promote PA, it has reached masses of users and has shown to have the potential to influence their health behavior at least in the short term [25]. Long-term results are rare, but it seems that the novelty effect tends to wear off with time, and after 3 months, 80% of players stopped using the app [26].

Direito et al [27] assessed the effect of 2 smartphone apps, 1 immersive and 1 nonimmersive app, on cardiorespiratory fitness and PA levels in healthy young people. Both apps consisted of 8-week training programs, whereby in the immersive app the training program was embedded with a story where the user has to collect supplies and protect a town from zombies. After 8 weeks, they were not able to report any intervention effect compared with a CG in both apps. Adherence to app use was a major concern during their investigation [27].

Garde et al [28] evaluated another smartphone app called “MobileKids Monster Manor,” in which behavioral psychology, positive peer pressure, and rewards are used with a monster character theme to increase PA in healthy adolescents. In a school-based environment, this intervention increased PA over a short-term period [28].

Several limitations should be considered when discussing this study protocol. In the phase-I evaluation, one-on-one interviews carry the risk of social desirability bias, where participants may provide responses perceived as socially acceptable rather than expressing their true opinions or behaviors. The phase-II evaluation carries the risk of the Hawthorn effect, which implies the awareness of being observed and studied that impacts people’s behavior. Based on this effect, PA levels might be higher than normal throughout the measurement period of 2 weeks.

Overall, digital health approaches provide easy and wide reachability at low cost and are age appropriate and attractive for the target group of adolescents. Strategies have to be developed to apply digital health approaches in the best possible way for activity promotion. The study will help to determine the efficacy, applicability, and user experience of a gamified activity promotion application in children and adolescents.