Video games offer a interesting approach for enhancing educational experiences across various domains. Whether repurposing existing games, such as Sim City for teaching budget management, or developing dedicated serious games, they enrich the spectrum of educational resources available. Nevertheless, creating immersive gaming and learning environments presents challenges. The absence of consensus on comprehensive tools or models poses an initial hurdle. Furthermore, designing such experiences entails intricate considerations, including multidisciplinary collaboration and the inherent complexity of open nature of learning experiences. Our proposed ontology addresses these challenges by integrating concepts from education, immersive game design, and virtual environments. This integration facilitates the alignment of learning objectives with game-design elements, leveraging the multi-agent systems paradigm for coherence. Serving as a semantic hub, our ontology enhances communication among interdisciplinary teams by employing clearly defined terms. Additionally, it provides a robust conceptual framework to navigate the complexity inherent in educational game development. We assess the efficacy of our ontology by instantiating it with several existing games or game engine. This instantiation validates its expressiveness and completeness, while logical consistency is confirmed through inference engine verification. Through these efforts, our ontology emerges as a valuable tool for advancing the design and development of educational video games.