I find the concept of "aji" especially fascinating when it comes to Go. The word means roughly translated means something like "taste", and as a go concept it refers to set of possible moves and continuations that can dramatically alter the local situation. For example, if there is a weakness in the opponent formation somewhere on the board because of the mistake opponent just made, but the opponent is able to somehow defend it under direct attack, I would most likely play away from this weakness for now, and try to steer the game so that the aji surrounding that weakness could be used as much as possible.

If the weakness was a possibility of a cut, which would totally work if you could get move A, an influential move that looks at the center of the board and works fine for you, instead of reaping the benefits straight away(playing A so now you got a nice influential move while opponent has to protect), you'd most likely want to go and start a running fight elsewhere on the board, and try to steer the fight so that A becomes a crucial move in it, so then opponent would face a choice, protect the original weakness, the possibility of a cut, or protect this new running group.

Leaving aji open and trying to get as much out of it as possible is, for me, the core of the game, but unfortunately I can't see any equivalent in rationality directly. Anyone else, any ideas?