Computational thinking is a discipline poorly mastered by elementary school teachers. To help teachers address these skills with their students, we develop the SPY game. In this paper we conduct a didactic analysis of the game and we propose a tool to describe the competencies targeted by the game based on game mechanics. The proposed tool has been applied to describe 21 of the 26 PIAF skills (a skills base on computational thinking). We show how these descriptions provide to teachers and designers micro information about the active skills in a level or macro information about the evolution of a game scenario complexity.