Halfgate is the default version of Plainsgate. The only way to unlock Plainsgate is to take Azure as your final tour of duty during the Conquest and specifically order the Scarlet Chorus or both armies to defend Plainsgate. It is then visited by starting The Tiers Will Shake (Disfavored), Cairn's Final Song (Chorus), Unlikely Allies (rebels), or Blood Trophy (anarchist).
An otherwise unremarkable pit stop that marked the eastern border of the great Stone Plains. With the collapse of the plains and the formation of the Stone Sea, the village became one of the few surviving human settlements in the region. It was helped by the fact that as far as Azure's cities went, it was one of the smallest and most impoverished settlements and was thus skipped over by the Chorus. Of course, that turned out to be quite the advantage in the long run, as it destined it for... Not greatness, but notability.