This epistemic characterization of Nash equilibrium requires mutual knowledge and rather than beliefs. The result fails when agents can be mistaken about the strategy choice of the others. This has lead some authors to criticize this epistemic characterization: See Gintis (2009) and Bruin (2010), for instance. How could the players ever know what the others are choosing? Is it not contrary to the very idea of a game, where the players are free to choose whatever they want (Baltag et al. 2009)?