Humanoid robotics is an emerging field striving to deploy technological devices capable of resembling and mimicking the human form. Primarily, the capability of human-like robots to interact with people has proved to be contributory in areas such as education and caretaking, but less so in adult training. In this study, we outline the design and experiment of an escape room training activity facilitated by a humanoid robot (HR), NAO. An escape room is a gamified activity where a team of players must complete a series of challenges to "escape from the room" by opening four locks in a limited amount of time. Opening each lock required the team to find hints and solve problems mediated by NAO. During the activity, NAO provided ongoing feedback on the team's performance. Ten experts evaluated the experience and were asked about their overall assessment of the activity and the added value of NAO as a mediator. The results on the feasibility of NAO's serving as motivating tutor in adults' collaborative game-based learning were very encouraging. We believe this study marks the first step toward developing a generic template for learning and training processes supported by a HR.