<i>But really, this isn't the important part, because the forecast horizon of both games are finite, which means in both games at some point you have to stop looking at possibilities and evaluate board position of leaf nodes. And chess has a less-imperfect method for that.</i><p>Actually, that makes a big difference.  Because you can look ahead farther in chess, the intermediate scoring can be less accurate, as you have a real chance of looking far enough ahead to have turned your positional advantage into a material advantage.<p>Using the size of the board as a proxy for the number of legal moves, looking ahead N moves in chess requires evaluating approximately 64^N intermediate states, and go requires 361^N.  That means that with equivalent computing power, looking ahead N moves in chess will let you look about N^0.177 in go.  Thus, a computer that can look ahead 40 moves in chess wouldn't quite be able to look 2 moves ahead in go, without very aggressive pruning of the moves that it considers.