well, technically the number of possible moves in a game of chess is believed to be infinite
which means that no program or computer, however powerful, could simply calculate its way to victory
in fact most good chess playing programs have the benefit of centuries of human analysis of the game of chess built in, with standard openings and past grandmaster games on which to base their quantitative analysis of the "strength" of a move. these provide a guiding framework which help the program to select which candidate moves to spend its time considering..
this should put into context the stage of development of game playing AIs that play other games like M2TW.
chess AIs have a head start of several centuries of human knowledge. it's unlikely M2TW (or any similar computer game) will be played for as long and be studied so deeply and comprehensively by so many highly intelligent and talented human players (we at the Guild can only do so much!)
this is not to say that it's impossible to create a challenging M2TW AI, but it should go some way to showing that the level of AI achievement is actually quite high when you consider the starting point - weeks or months of testing, rather than centuries, have gone into creating a set of rules to guide this AI in playing M2TW.
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