The overall objective of the present study was to investigate associations between emotions, flow experience, intrinsic motivation, and playing performance in a math game competition. Finnish 3rd – 6th graders (n = 251) participated in a math game competition relying on intra-classroom cooperation and inter-classroom competition. During a three-week competition period, students were allowed to freely play a digital rational number game founded on number line estimation task mechanics. An online questionnaire was used to collect students’ experiences after the competition. The results indicated that students who experienced higher positive emotions in the competition also experienced higher levels of flow. Findings also showed that intrinsically motivated students experienced more positive emotions and higher flow as well as indicated a higher willingness to participate in math game competitions again as compared to low intrinsically motivated students. Moreover, current results provided some evidence that game based competitions might engage also lower performing students.