The achievement specifies vanquisher difficulty, but while in a non-vanquisher game, it still reports the level of happiness achieved in the current map. I don’t know if this could trigger the achievement or if it is just a progress indicator that doesn’t care about vanquisher or not. Other achievements that do specify vanquisher, like Vengeful Vanquisher, remained at zero while I completed Vengeful Survivor in this same map.
To clarify, I did not compare the percentage in this achievement screen with the actual happiness on the map because, at the time, I was playing in a non-vanquisher game and felt it shouldn’t matter. But there may be another issue at hand here. I am also detecting the same 79% completion towards this achievement in a vanquisher map where I have so far achieved up to 99% for a moment. For a while I have been struggling to get water to every house before they consume it.
