The game revolves around Kerrigan attempting to exact revenge on Arcturus Mengsk for his many sins, and that involves reassembling her old swarm, in addition to picking up new allies along the way.
The Chinese believed that the rising of Arcturus, the fourth-brightest star in the sky, caused spring to burst forth, while the Egyptians thought that the appearance of Sirius, the brightest star in the sky, brought about the annual flooding of the Nile.