This paper presents ScenLRPG, a specific method, based on a graphic formalism, for designing game-based learning systems in a vocational training context.This paper presents ScenLRPG, a specific method, based on a graphic formalism, for designing game-based learning systems in a vocational training context. We detail in a first part the theoretical background for our hypotheses on three properties such a method should display: (1) supporting the elicitation of the relevant learning goals and game mechanisms so as to boost learner motivation, (2) enabling a team of designers to collectively build and manipulate a game-based learning scenario and (3) improving designers creativity. Part two presents an evaluation study performed using a tangible version of the method, based on a board game. The aim of this study was to test whether the method effectively favours designer collaboration and provides designers with fresh ideas, but also to gather the pros and cons of a board game-based design tool versus a computer-based environment. The final part is devoted to an analysis of the obtained results.