The UNSC Spent years trying to uncover why the covenant avoided this planet. Unfortunately, when they found out it was to late. They had already awoken a weapon of old. Within hours it killed everyone at the facility. Your job is to find out what the weapon was, and to either suppress it, or to destroy it. But, be warned. Not all that it infected, are dead. Some are under its control.
UPDATES
MAP Update (1): The large building near human spawn as been changed, and can now be entered, as well as the roof is now accessible. A crashed, and unstable covenant ship was added to the map towards the north end. a SPNKR, and a BR83SR where added. 3 new holdouts have been added, but only one is accessible from a switch in another holdout. Map design is set up so that the structures look unfinished as the UNSC had never had a chance to finish building the site.