The Gloam is a supernatural entity which was first seen residing in The Park Zoo in Blough City, and is connected to the City and the Tunnel Project. It affected the minds of the animals within the zoo, making them want to stay within the zoo despite the depressing conditions.
After Chanti visited The Park Zoo, she was affected by the Gloam. Rupert was also affected by the Gloam after Chanti carried him through the Tunnel to return to Bluff City.