The Orb Alliance is the force of the alien Orbs who invaded Earth in 2001 by dawn's first light.
As for New York, they devastated the city and banned communications. Without maintenance, vandalism skyrocketed and living quality eroded. Buildings were destroyed, boarded up or taken by the Orbs' operations. Meanwhile the Orbs attempted to "purify" Earth's atmosphere for breathing more easily. For humans this gave a rotten smell to the air and a red tint to the sky. This also made them sluggish, easier to control and caused some peculiar behavior.
Other operations in New York included.
*Bellevue Hospital: processing humans into food and hatching their young.
*Grand Central Terminal: Orbs' fleet of ships.
*Statue of Liberty: "purify" the air by pumping out fumes and the main radar and anti-air defense systems.
*Empire States Building: central computer system and main radio transmitter.
Orbs forbid communication and expression of humans. They all wore the designated brown robes and hide their faces. Speaking meant certain death. They were allowed only for music and colored robes when celebrating. Humans were allowed to live only in restricted areas and used mainly for food. Furthermore, they were all entered in the Human Database Service and implanted with a tracking disk in the back of their neck which recorded all movements in the Human Tracking Records database.
Since the disks did not track one's identity, nor work underground, the Underground resistance was formed by humans to drive the Orbs off New York. The Manhunters were humans employed as Orb agents that would investigate off-normal behavior and track wrongdoers' identity.