This exploratory multiple case study attempted to examine whether game-based learning activities had any impacts on students' academic performances and behaviors, and what perceptions the teachers had toward implementing games into their classrooms. Data used in this study included 101 students' pre and post-test scores, and four structured written reflection papers by four STEM classroom teachers. The results indicated that students' academic performances improved during the week GBL was implemented. In addition, their behaviors were noticed to change positively. Finally, teachers' perceptions about GBL changed before and after they integrated the games into their classroom. The study was concluded with discussions, implementation of using GBL in STEM classrooms and suggestions for future studies.