The aim of this systematic literature review was to examine the empirical evidence for the effectiveness of digital games on second language learning between 2014 and 2018, with a focus on participants 6–18 years old. The initial search yielded 578 results, from which a total of 26 articles were included in the final content analysis. The analysis of the included studies revealed: (1) the majority of studies were conducted with a mixed methods design; (2) most studies used computers as the gaming platform; (3) the most common game genre was educational games or educational mini games; (5) most games were designed for learning; (4) research was mainly conducted in East Asia and the Middle East; (5) the primary context of study was within a formal learning environment; and (6) the target language was usually English. Further analysis suggests that digital learning games (DLGs) may benefit players' language acquisition, affective/psychological state, contemporary competences, and participatory behavior. An inductive analysis revealed six key game features highlighted within the studies that influenced the outcomes: ease-of-use, challenge (at one's zone of proximal development), rewards and feedback, control or autonomy, goal-orientation, and interactivity. In addition to game features, associations between context and outcomes were also explored: studies conducted within a formal learning environment, with or without teacher facilitation, resulted in mostly positive language acquisition results, meaning DLGs can be implemented successfully within schools. Based on the overall findings, it is clear that DLGs are an effective tool, but future research should explore how they can best be implemented in the classroom setting.