there was lots of dialouge in vietcong besides the commands you specifically ordered. During points in the mission, say, when you went into a vc tunnel for the first time, you character would say stuff to the effect of "why am I always the one that has to go down" or something. They had no actual impact to the gameplay, but by the end of the game, I was assosciating the voice and attitude of the recorded dialouge with the way I played my character.