Purpose: This paper provides a general review related to a wider project, aimed at developing a mobile game-based app on Education for Sustainable Development within a smart learning city environment. It aims to address guidelines for a new action-oriented transformative pedagogy that is essential for the development of key competencies for sustainable development based on literature review and on the exploration of a previously created mobile game-based app -- the EduPARK app. Design/methodology/approach: This work gives continuity to the developed work, through a qualitative interpretive methodology of case study. Its main objective is to analyze the opinion of Higher Education students, who have experienced the EduPARK app, in what concerns the impact of the educational strategy into: (1) learning value, (2) authentic learning, (3) lifelong learning, and (4) conservation and sustainable habits. Data collection instruments involve students' reflections triangulated to a questionnaire. Findings: The study finds that the potential for promoting conservation and sustainable habits is widely recognized by app users, although they mention that this aspect can be further explored. This legitimates the relevance of the new mission -- EduCITY, which focuses on enhancing sustainability key skills of citizens who participate in extension game-based activities on strategic paths in the city. Originality/value: This paper comprises a set of guidelines and best practices for educational stakeholders and decision makers in order to enhance a wider integration of this outdoor mobile innovative approach in education, promoting smart and sustainable attitudes of citizens within the cities.