This happened awhile ago but Nier is getting a sequel.
In the distant future, Earth has been invaded by aliens using Living Machines to win their war. Manking retreats to the moon where they stage a counter attack using advance androids called YoRHa to try and retake the planet. You play as YoRHa No. 2 Model B, who is one of the lone survivors of the counter-offense. Now you explore the remains of Earth and battle the Living Machines to retake it for mankind.