Entropy in a chess game For entropy to be correct, i mean, that increases over time, in a chess game, there should be more options as game time goes on. But it's the opposite. Why?
 A: The thermodynamic entropy certainly increases during a chess game. For example, if you have two human opponents, they are each breathing, pumping blood, digesting, metabolizing -- all of these processes create heat. If one or more of the opponents is a computer, irreversible processes generate heat in the computer and will also increase the thermodynamic entropy. So the second law of thermodynamics is not contradicted by the existence of chess.
If you are referring to entropy in the sense of counting the number of possible chess position configurations -- essentially, an information theoretic entropy instead of a thermodynamic entropy -- then the second law of thermodynamics does not make any statements saying the entropy of a chess position should increase, so there's no reason (a priori) to expect the entropy to increase or decrease.
However, the number of possible board positions does increase in chess as you increase the move number, so in that sense the entropy defined in that way does increase. Another way to say that is that your odds of guessing the correct position go down with time. For each previous board position, there is typically more than one legal move, so the number of available positions is increasing. Eventually perhaps you reach a steady state where all positions have resulted in a draw or win, you might consider that a kind of "equilibrium state."
A: I'm not sure this is a fitting interpretation of classical entropy.
Rather, from the very beginning you now everything about every field on the chess board. If I ask you about a randon field, say, C6, then you can with a blindfold on tell me exactly which chess piece, if any, that is located there.
But as game time progresses, you know less and less about each individual field and your guess will more and more often be wrong.
