The study is the second in a series of mixed-methods studies on the integration of The Sims 4, a life-simulation game, into language classrooms. In this study, the researcher explores the effect of game-based language learning (GBLL) on students' English communicative competence from three aspects, interaction, fluency and content, in a Japanese university. In class, students received instruction from the teacher on game language and gameplay skills, played the game on their own and presented gameplay stories. The presentations were recorded for evaluation. Surveys were also administered for students' perceptions on the GBLL classroom. Results showed that no clear improvement in communicative competence was suggested by quantitative evaluation. Qualitatively data, however, indicated that the game afforded students interesting events and proper expressions in presentations and that the teacher played a vital role in ensuring ample interactional opportunities and linguistic support. Suggestions for future research in classroom-situated GBLL were also proposed.