This paper reports participants' perceptions of gaming simulations (g/s) before and after a 15-week course, using a semantic differential method to analyze two groups of students. From 2011 to 2013, approximately 600 students were asked to rate their perception of g/s on a five-point scale. While the two groups showed similar tendencies, one group showed a clearer attitude than the other. A noteworthy result was the groups' changed perception of g/s from simple to complex after the course. The results of factor analyses showed two possibilities: the "complexity" factor changed from negative to positive while the "challenge" factor needed to be obtained. Differences in students' readiness for g/s were discussed.