This action research study examined the effects of review games using Kahoot! on students' quiz scores as well as student engagement. The study was conducted in a high school geometry classroom at Tiyan High School (THS) in Barrigada, Guam. This study consisted of a sample size of 42 students in the 10th through the 12th grade. The data collected during the six-week period of the study included students' quiz scores and number of off-task students for both the experimental group and the control group. Overall averages of the quiz scores and number of off-task students from the class that participated in review games using Kahoot! were compared to the class that received a teacher-led review. Results show that the use of Kahoot! during review games produced higher overall quiz averages and more observable student engagement when compared to the outcomes of a traditional teacher-led review. With these results and some limitations, recommendations for future similar studies were made.