This is and Alien Single Player map.
As an Alien you will assault the Hadleys Hope colony on LV-426. Your task is to kill all 158 colonists. You will be assisted by AI Alien escorts to achieve this Objective.
Completing the map successfully will unlock an achievement award, 'Sole Survivor':
The USCM haven't arrived on LV-426 yet and you are the only person left alive in the colony over-run by Aliens. Will you survive? Can you escape..?