The article discusses how players in a game make decisions based on what they know and believe about the game and each other. It shows that when two players have mutual knowledge of certain things, their guesses about each other's moves can be a Nash equilibrium. For games with three or more players and a common starting point, mutual knowledge of certain factors and common knowledge of guesses can also lead to a Nash equilibrium. The study reveals that common knowledge is not as crucial as previously thought in determining Nash equilibrium.