This article analyzes the impact of a computer simulation (business game) on the users' perceived learning. The theoretical model developed in this paper is derived from the collaborative learning and the Human-Computer Interaction assumptions. The hypotheses relating groups' dynamics and the user-computer interface design with the users' perceived learning are tested using the business game "FirmReality", on an 89 respondents sample. Multiple regression and qualitative results show that, in a computer based simulation context, perceived learning is more influenced by human-computer interaction factors rather than groups dynamics.