Individual gameplay interest is affected by numerous factors and a competition setting is also of importance as there are factors that need to be managed. To understand the motivational variables related to an educational game competition, this study explored the interrelatedness between self-efficacy, competitive anxiety, and gameplay interest in a one-on-one Chinese idiom string up game competition. Effective data from 278 elementary school students from grades five to six were collected and subjected to confirmatory factor analysis and structural equation modeling. The results of this study showed that the higher the level of competitive anxiety, the lower the degree of gameplay interest (i.e. "Like", "Enjoyment", and "Engagement"). In addition, self-efficacy in learning Chinese idioms was negatively associated with competitive anxiety. The implication of this study contributed towards understanding that low competitive anxiety is more facilitative to interest in gameplay. The results also suggested that enhancing self-efficacy in a specific task can eliminate anxiety and support players' interests to play the game in a competitive setting.