Since the whole idea of Purity is to preserve humanity in its current form, it isn't surprising that Purity aesthetics look much like we would expect of a space-oriented mankind in the near future. Architecture is characterized with solid, cubic shapes in gold and red which look a lot like modern cities; units appear mostly human-shaped, and tank-like. That is because Purity depends mostly on armored suits and exoskeletons to enhance traditional soldiers, or else on solid, massive machines commanded by soldiers.