Curiosity is the best driving force for learning; keeping learners curious by engaging them via gaming has been regarded as a desirable approach to education. Virtual Interactive Student-Oriented Learning Environment (VISOLE) is a pedagogical approach to serious gaming that we have proposed. Based on the VISOLE pedagogy, we developed Farmtasia ® , a multiplayer online serious game based on a thematic topic, Agriculture, in the Hong Kong senior secondary geography education curriculum. Drawing on the notion of virtual mentoring, we aim to further enhance the design of the game by introducing a number of non-player characters (NPCs) to scaffold non-gamer students' learning in the gameplay process. This chapter reports a learning experiment in which we compared the pedagogical effectiveness of the revised version of the game with that of the original version, in terms of non-gamer students' knowledge acquisition. The results show that the experimental group students (who learned with the revised) significantly outperformed the control group students (who learned with the original), with a considerable effect size.