This study evaluated the effectiveness of a mobile application called Shadow's Edge, with or without a printed self-awareness guide, in improving well-being and emotional resilience among Colombian youth aged 18 to 22. A total of 184 participants were randomly assigned to three groups: one used the app only, another used both the app and the guide, and a control group received delayed access. Participants completed psychological assessments before and after the intervention. The main outcomes included changes in well-being and resilience measured with standardized scales. Results showed that the app improved well-being and resilience in the short term. However, adding the guide did not produce additional benefits. The study highlights the potential of digital mental health tools in promoting emotional well-being among young people in low- and middle-income countries.

This study is a randomized clinical trial designed to evaluate the effectiveness of a mobile mental health application (Shadow's Edge) and a printed self-awareness guide (GSEA - Guide to Self-Awareness) in improving subjective well-being and emotional resilience among Colombian youth. The study was conducted in response to the growing demand for accessible, evidence-based mental health tools in low- and middle-income countries (LMICs), where structural barriers such as inequality, poverty, and conflict limit access to traditional mental health services. The COVID-19 pandemic further highlighted the need for remote, scalable solutions to address emotional well-being in youth populations.

Shadow's Edge is a narrative-based digital tool developed by the nonprofit Digging Deep Project. It combines principles from narrative therapy, positive psychology, and existential psychology. Through writing prompts and creative expression in a post-apocalyptic fictional setting, users are guided to explore their emotions and build resilience. The game environment fosters engagement by allowing users to rebuild a city devastated by a storm-a metaphor for personal adversity. It has been previously evaluated in different contexts, with promising results in mental health promotion and resilience-building among adolescents.

The Guide to Self-Awareness (GSEA), developed as a printed complement to the app, incorporates socio-emotional learning strategies to deepen reflection. It includes structured exercises that promote mindfulness, emotional regulation, goal-setting, empathy, and communication skills. Both tools were culturally adapted to the Colombian context between 2021 and 2022, involving feedback from local adolescents and youth leaders.

A total of 305 young people expressed interest in the study through an open call disseminated via youth organizations. From these, 210 met the eligibility criteria and were randomized into three groups using the randomizeR package in R. The eligibility criteria included being between 18 and 22 years old, residing in Colombia for at least 6 months, and not being regular users of high-action video games (based on guidance from the app developers, who indicated that such users may have lower engagement with narrative-based tools). Participants with prior experience using Shadow's Edge were excluded. The final sample included 184 participants.

The groups were structured as follows:

App Group: Participants used Shadow's Edge only.

App + Guide Group: Participants used Shadow's Edge and completed exercises from the GSEA.

Control Group (Waitlist): Participants received delayed access to both tools after a second baseline measurement.

Data were collected using three validated instruments:

• WHO-5 Well-Being Index (Campo-Arias et al., 2015 - Colombian validation): Measures subjective well-being over the last two weeks using five items on a Likert scale.
• Abbreviated Resilience Scale (EAR) (Rodríguez-Rey et al., 2016 - Spanish validation): A six-item scale assessing perceived resilience.
• Abbreviated Resilient Coping Scale (EAAR) (Trejos-Herrera et al., 2023 - Colombian validation): A four-item scale measuring resilient coping behaviors.

Measurements were taken in person at baseline and at 4 and 8 weeks for the intervention groups. The control group was evaluated four times: twice prior to gaining access to the tools and twice after. All instruments were administered in print. Compliance with the app usage was monitored via daily digital progress logs and backend usage data linked to anonymous codes. Participants were encouraged to use the app for at least 20 minutes daily.

Statistical analysis was conducted using mixed-effects regression models in R, controlling for group assignment, age, sex, and the number of words written in the app journal (used as a proxy for engagement). The analysis aimed to determine changes over time in each outcome measure, as well as between-group differences.

Inclusion Criteria:

• Age between 18 and 22 years at the time of enrollment
• Resided in Colombia for at least 6 months prior to the start of the study
• Provided informed consent to participate
• Not a frequent user of high-action video games (e.g., first-person shooter or battle royale formats)
• Had not previously used the Shadow's Edge mobile application

Exclusion Criteria:

• Any participant sharing a household or close familial relationship with another enrolled participant (to prevent contamination across study arms)
• Failure to meet any of the inclusion criteria

De-identified individual participant data (IPD) related to primary and secondary outcomes (WHO-5, EAR, and EAAR scores), collected at all time points.

Data will be available beginning 6 months after publication of the main findings and for up to 5 years thereafter.

Data will be made available to qualified researchers upon reasonable request for purposes consistent with the original study objectives. A data use agreement will be required.