One manga that might be similar is 'Dark Moon'. It has a similar dark and mysterious atmosphere as 'City of Darkness'.
I'd recommend 'Shadow Town'. Both have elements of mystery and a brooding tone like in 'City of Darkness'. Also, the character development in both is quite compelling.
Chapter 454, "Are these two people crazy?!", is the clearest early answer because it turns Sister Li's situation into a concrete plot event. The chapter gives readers a real answer by opening on Shang Shuyue felt that following Jiang Li was the best decision she...
Chapter 545, "Kiss Me", is the clearest early answer because it turns Xu Cheng's situation into a concrete plot event. The chapter turns that into something concrete by moving from Truth or dare, I still choose dare!" He just didn't believe it, Jiang...
Chapter 744, "Dig Three Feet into the Ground to Find Her!", is the clearest early answer because it turns Jiang Li's situation into a concrete plot event. The chapter turns that into something concrete by moving from What?!" Wen Jiaojiao directly questioned out loud, "On what basis are...
Chapter 788, "Don’t be so fierce, I'm scared", is the clearest early answer because it turns Song Xue's situation into a concrete plot event.
Chapter 629, "The Family is Going to be Gone", is the clearest early answer because it turns Jiang Yan's situation into a concrete plot event. It opens with Even after training under Jiang Li for so long, they couldn't...
Chapter 533, "Sister Li, When Did You Become a Clamp?!", is the clearest early answer because it turns Yu Li's situation into a concrete plot event. It opens with The sycophant had gone crazy too. and closes on Although at the time he said it was a gift from the young master of....
Chapter 725, "Illegitimate Children Can Also Inherit Property!", is the clearest early answer because it turns Jiang Mingchuan's situation into a concrete plot event.
Chapter 634, "All Villains", is the clearest early answer because it turns Yu Li's situation into a concrete plot event.