Serious games are becoming more popular because they provide an opportunity for learning in a natural environment. Although many concepts included in cybersecurity awareness training are universal, many forms of training fail because they are based on rote learning and do not require users to think about security concepts. The main objective of this study is to design a candidate cybersecurity awareness training tool which provides an environment for helping users to understand security concepts while playing a game. To reach our goal, we applied a newly developed model, which is Activity Theory-based Model of Serious Games (ATMSG), to design our own game. According to the design, we implemented a game demo and assessed its gameplay. The results indicated that the story gameplay can help players improve their understanding of cybersecurity problems and resolutions.