This paper presents the development process and preliminary result of testing a game-based intervention aimed at promoting human papilloma virus (HPV) vaccination among adolescents aged 11-14. Guided by the Social Cognitive Theory (SCT) which explains the mechanism of desired behavioral outcomes through theoretical mediators (knowledge, self-efficacy, outcome expectations, facilitators & barriers), our transdisciplinary team use an iterative process to develop a game in partnership with Family Advisory Board (FAB) consisting of 4 parent-boy pairs, and 4 parent-girl pairs. We test the prototype of the game with half of the FAB to examine gender, developmental and cultural appropriateness of the game content, readability, physical characteristics of the avatars, and reward mechanisms in the game. The design of the game addresses several constraints commonly faced by interventions implemented in clinical settings. It describes the strategies that can be used to overcome these constraints and provides guidance for future development and proliferation of such interventions for other vaccines.