The COVID-19 pandemic has significantly impacted students' motivation for learning. As students return to schools in the post-pandemic era, their motivation for learning continues to deteriorate due to challenges in adapting to the new educational norms. This study aimed to enhance the motivation of secondary school students towards learning chemistry, particularly during the period when their motivation has tended to be low upon returning to regular schooling after the pandemic. To achieve this objective, the researchers developed and implemented a self-designed game-based learning approach called STEM-PT Traveler during lessons focused on the periodic table. STEM-PT Traveler incorporated elements of enjoyable learning and play, introducing an interdisciplinary perspective to periodic table lessons. The effectiveness of STEM-PT Traveler in improving motivation was compared to an alternative student-centred, non-game-based learning approach using an explanatory mixed-method design. Two intact classes from a public secondary school were randomly assigned to two groups--one group utilized the game-based learning approach (N = 45), while the other group employed the non-game-based approach (N = 46). The multivariate analysis of covariance (MANCOVA) findings from pre-test and post-test questionnaires administered before and after treatment revealed significant differences in overall motivation and in the subscales of intrinsic motivation, career motivation, and self-efficacy. Non-significant differences were observed for grade motivation and self-determination. Qualitative interviews conducted with both groups after the treatment provided additional insights into the questionnaire outcomes. Specifically, during the interviews, students highlighted that the game facilitated engagement with the periodic table elements due to their intrinsic value. Additionally, the game provided a career perspective and instilled a belief that excelling in chemistry is instrumental. This study suggests that a game-based approach is an effective alternative to the predominantly used teacher-centred teaching of the periodic table and advocates for the integration of interdisciplinary perspectives into lessons on the Periodic Table.