In a “perfect game”, there is perfect information. What this means is that all the players are aware of the current state of the game and are fully aware of their options. Chess is an example of such game.
There are very few real-life scenarios that follow this pattern. More commonly, not all the information nor the state of the system is available to all the players/users.
Under the most basic scenario – known as the Normal Game – there are ‘n’ players, each of which have perfect information and each player is aware of the pay-off function and striving to win. The pay-off function, however, depends on how the other participants play the game and their strategies.