Digital serious games are increasingly recognised as valuable tools for fostering student engagement and supporting active learning processes in formal educational contexts. Within the field of heritage education, however, empirical evidence concerning teacher-created games and their pedagogical effects remains limited. This study examines the educational impact of a digital serious game designed by teachers using RPG Maker MV to support the teaching of Social Sciences and local cultural heritage. The game, Misterios de Olivenza, integrates historical, geographical, and cultural content related to the municipality of Olivenza (Extremadura, Spain) through exploratory gameplay and problem-based activities. The research involved 86 primary education students aged 10–13 and employed a validated questionnaire to analyse gameplay experience, motivation, and self-perceived learning, with attention to age and gender differences. Results indicate high levels of enjoyment, motivation, and perceived learning, with no statistically significant differences by gender and limited age-related variation. A moderate positive correlation was identified between motivation and self-perception of learning, suggesting that engagement plays a key role in students’ educational experience. The findings highlight the pedagogical potential of teacher-created serious games for heritage education, while underscoring the importance of careful curricular integration and adequate scaffolding to maximise educational effectiveness.