Game-based vocabulary learning that is well documented to improve students' vocabulary learning outcomes is gaining increasing attention. However, no consensus has been reached regarding the impact of game-based vocabulary learning application (APP) on the vocabulary learning achievement, motivation, and self-confidence among Chinese EFL (English as a foreign language) students, so large a population that should never be neglected. To address the issues, a total of 70 college students in two groups participated in a quasi-experiment. One is the experimental group in which students received the game-based vocabulary learning; the other is the control group in which students received the conventional paper-based wordlist learning. Each group consisted of 35 students. The experiment was carried out to evaluate how the implementation of game-based vocabulary learning influences students' vocabulary learning achievement, motivation, and self-confidence. In addition, a regression analysis was exploited to examine the influence of motivation and self-confidence on vocabulary achievement. Results demonstrated that the game-based vocabulary learning APP benefited students in vocabulary achievement, motivation, and self-confidence. Furthermore, learning self-confidence and motivation did not predict learning achievement. Implications of the study were also given.