Games have been regarded as a potential vehicle for enhancing student learning. Previous studies mainly focused on learning outcomes; however, the learning processes and dynamic in-game behaviours of students who are immersed in a game context are relatively undiscovered. The purposes of this study were to develop an educational game, "Bio Detective," to facilitate student science learning and to investigate how game immersion experiences are related to in-game behavioural patterns. The study included 128 7th graders (12-13 years old). A mixed-method approach collecting both quantitative and qualitative data was employed, and an integration of cluster and sequential analysis was used. The findings showed that the students were able to learn from playing "Bio Detective" because significant improvements in science learning outcomes were obtained. The students who were totally immersed in "Bio Detective" acted more like expert problem solvers than their counterparts with no immersion experiences. They had better problem-solving efficiency, and their behavioural patterns revealed that they had more heuristic and analogical thinking strategies. Interpretations and limitations are further discussed.