Formative peer assessment is widely used in education to foster student learning. However, it is critical to provide students with assessment training before engaging them in peer assessment, as students may not be capable of understanding marking criteria and critically assessing their peers. The present study examined the effects of gamed-based assessment training on students' assessment skills and intrinsic motivation. A sample of 48 students participated in two peer assessment training modules; one control group was given the traditional, calibrated training and the treatment group received the game-based training. Data analysis indicated no significant difference in students' assessment skills between the two groups. Nevertheless, students in the game-based group showed a significantly higher level of intrinsic motivation than students in the calibrated training group. Qualitative analysis of students' reflection essays confirmed the quantitative findings that game-based training may have improved students' intrinsic motivation. Implications and limitations are discussed.