The present research examined the effect of digital role-playing game-based learning on high school students' critical thinking ability. Playing a digital game designed with RPG Maker and whose story lines featured critical thinking questions, a total of 32 high school student participants were given a learning context to practice critical thinking skills repeatedly. A quasi-experimental design was implemented to explore how students' performances in critical thinking skills and their learning motivation changed after participation in a four-day workshop camp. The results of the study showed that student participants achieved significant progress both in overall critical thinking performance and in learning motivation. Similar studies on the effectiveness of digital game-based learning on learning performance and learning motivation among students were also compared in lieu of the results of the present study. Both the quantitative and qualitative results of this study not only agreed with a majority of previous research findings on students' learning performance and learning motivation, but revealed some distinctive pedagogical qualities among different skills of critical thinking. Practical suggestions were also provided to help future studies and instructional designs of digital game-based learning achieve effective learning and enhance learning motivation among students.