Helping learners to easily develop their skills and adapt to their new profiles, are among the biggest challenges of the actors of the training field. The JEN.lab project aims to offer innovative perspectives for learning based on the design of digital epistemic games. Though designing activities are complex especially for teachers. The research effort presented in this paper is part of the JEN.lab project. We aim to study problems related to modeling and designing digital epistemic games (DEG). We propose a co-design process and an assistant tool to guide teachers to design DEG, called ADDEGames.