Abstract

This study investigates incidental vocabulary acquisition among English as a foreign language (EFL) learners through engagement with video games, particularly the mobile RPG Genshin Impact and the mobile first-person shooter Call of Duty: Mobile (CODM). Although the field of digital game-based language learning (DGBLL) is expanding, there is a paucity of research comparing the effectiveness of different genres or concentrating on specific, highly engaging mobile games. Forty intermediate EFL university students in Iran participated in a six-week study. They were divided into experimental groups (Genshin Impact, CODM) and control groups. Quantitative data from Vocabulary Knowledge Scale (VKS) pre/post-tests assessed vocabulary gains, while qualitative data from focus groups, stimulated recall interviews, and gameplay logs examined learning experiences and strategies. Analysis of variance (ANOVA) and post-hoc tests revealed that the Genshin Impact group outperformed the CODM group in vocabulary gains, though both experimental groups showed statistically significant improvements compared to the control group. The findings suggest these games hold significant potential for vocabulary development at the intermediate level, though efficacy for lower proficiency remains a question for future research. While CODM exposure was more contextually sparse, qualitative analysis revealed the critical roles of contextual richness, repetition, motivation, and learner agency in Genshin Impact. Commercially successful mobile games, especially narrative-rich role-playing games like Genshin Impact, prove effective for incidental vocabulary learning, mainly due to contextual embedding, high-frequency exposure, and intrinsic motivation. This study bridges gaps in genre comparison and transferable vocabulary acquisition, supporting the integration of such games into supplemental language learning contexts.