[olympus]

I don't think this is quite what was meant by the "everything is known" comment. I may not know what Carlsen is going to do for his next move, but I could certainly come up with a list of every possible move. The rules of chess won't change in the middle of the game and he won't suddenly be able to castle twice.

Chess is a game of perfect information where nothing is hidden from either side. Theoretically the white player should be able to win or force a draw every single game. It just doesn't happen that way in real life because to construct a tree of every possible move and counter move and then pick the optimal branch is hopelessly complex with this game. But for checkers it's doable (the best checkers players will play flawlessly and games are won or lost on a single mistake), and you probably already have tic-tac-toe figured out.

Edit: dang, ninja edit where you just said almost everything I said.

[airframeng]

"Chess is a game of perfect information" - perfect but almost infinite/impossible to calculate even for the most powerful computers, within a finite timeframe. The number of legal chess positions is 10^40, the number of different possible games, 10^120. As a comparison, the number of atoms in the observable universe is estimated to be between 4×10^79 and 4×10^81.