What makes AI difficult in these games is pattern recognition of higher level strategic abstractions. A human player can recognize that placing a Go stone or a Terran command center projects some power in regions around that spot. The human can use intuitive pattern matching to assess when he has a superior force in an area and can push to a decisive tactical victory, even if the human isn't quantifying every move in precise terms. An AI must quantify every bit of power projection somehow, which becomes impossible with present computing resources in games whose possible state space quickly explodes into 10^10 or more possibilities.
It's actually a similar problem to computer vision. Identifying a battle front from the current state of a war game and recognizing the tactical possibilities is similar to edge detection in a photograph and recognizing objects. Humans do that essentially with highly parallel computations and lookups by billions of neurons. Until we get billion-core CPUs and billion-ported RAM, AIs will not have the same capability.
Source: I've done some development on AI for Civilization. It sits somewhere between Go and Starcraft in AI capabilities. Civilization is turn-based like Go, but the state space explodes far more quickly like Starcraft when you have 100 units which can each make a dozen moves in 100! different orders on a turn. (In Civ, the order on which units act each turn is extremely important, where workers lay down railroads for other units to move, or where you attack a city with artillery before the ground pounders.)
It's actually a similar problem to computer vision. Identifying a battle front from the current state of a war game and recognizing the tactical possibilities is similar to edge detection in a photograph and recognizing objects. Humans do that essentially with highly parallel computations and lookups by billions of neurons. Until we get billion-core CPUs and billion-ported RAM, AIs will not have the same capability.
Source: I've done some development on AI for Civilization. It sits somewhere between Go and Starcraft in AI capabilities. Civilization is turn-based like Go, but the state space explodes far more quickly like Starcraft when you have 100 units which can each make a dozen moves in 100! different orders on a turn. (In Civ, the order on which units act each turn is extremely important, where workers lay down railroads for other units to move, or where you attack a city with artillery before the ground pounders.)