Lack of female involvement in ICT field calls for new approaches to ICT education. Serious game is an effective tool for learning, so it can be used to motivate and engage female students to study Computing. Engagement elements for serious game were identified from previous researches and a conceptual model for gender-based engagement using serious game was constructed. In this paper, the model validation of a low fidelity prototype using heuristic evaluation technique for educational game is discussed. The heuristic scale was adapted from previous studies, comprise of playability and enjoyment constructs. In addition, educational elements items are also included. The scale was then validated for content validity, and a pilot study with four (5) HCI experts. Finally, five (5) experts from HCI, Game and Computer Networking subject evaluate the model using this scale. Results of the evaluation showed that the model’s constructs have good usability, playability, enjoyment. Future work will be to validate the model using high fidelity working prototype and user testing.