Vocabulary learning is vital for second language development, and the use of technology has greatly changed how second language vocabulary can be acquired. Some adventure video games were found to be beneficial for vocabulary learning. These games offer engaging plots, rich input, and immersive learning context. Despite these advantages, many games often include difficult vocabulary items and fleeting subtitles. Researchers have suggested that games can be modified to provide a more supportive environment. The purpose of the present study aimed to examine the effect of an adventure game and the game plus L1 keyword glosses on second vocabulary acquisition. Two classes were recruited and took a pre-test, post-test, and two-week delayed post-test and filled out a survey. The results indicated that the control group (i.e. game only) has significantly improved, suggesting that the gaming context alone can assist the incidental vocabulary learning. The experimental group (i.e. game with L1 glosses in the subtitles) significantly performed better in the post-test and delayed post-test. The findings indicated that L1 glosses helped to enhance noticing and to learn new words. It was clear that adventure games have great potentials for vocabulary learning, and additional lexical supports in gaming can further enhance vocabulary learning.