Bad City Blue was a strip in 2000 AD by Alan Grant and Robin Smith, about Bader City, a decrepit conurbation under a protective dome on an asteroid. When the story takes place, 90% of the city is slum. The first episode appeared in 2000 AD prog 468, in May 1986. Details of the plot can be found on the character pages of Blue, the strip's protagonist, and Teco, one of the supporting cast.
The series ended in prog 477, in July 1986. It was possibly the bleakest tale of urban decay ever told in 2000 AD, and certainly did a fine job of subverting the readers' expectations.