Game-based learning environments provide learning methods that better correspond with current students' requirements and habits and, as a consequence, engage students in the learning process. In this context, the design of most serious games mainly deals with the problem of, on the one hand, the amount of time required by students interacting within these interactive environments and, on the other hand, showing improvement in achievement related to formal learning outcomes. In that way, scaffolding approaches, which are devoted to providing corresponding instructional aids to students to facilitate the learning process to accomplish tasks that ordinarily cannot be performed by their own, are of high importance in assisting students' learning and can provide students with appropriate mechanisms to get more benefit from the use of game-based environments. Besides, since serious games in the classroom offer the promise of students' engagement, autonomy, motivation, and modelling potentials, it becomes interesting to scientifically explore and validate the impact of those game-based learning environments that integrate scaffolding in formal learning. Taking this in consideration, this paper presents a review of scientific literature on the application of scaffolding approaches in game-based learning environments. The focus of this work is twofold: 1) present research evidence on the impact of scaffolding approaches in game-based learning; and 2) identify trends and open research questions in the field. To this end, a systematically search online using the keywords 'game-based learning' and 'scaffolding' in a set of relevant scientific databases ( i.e., ScienceDirect, IEEE Xplore, SpringerLink, Scopus, Scirus, and Education & Information Technology Digital Library) has been carried out. Studies considered in the review met the criteria of describing game-based environments that have integrated scaffolding mechanisms. The main conclusions of this work draw the role of scaffolding approaches in game-based learning in the digital age.