Sopot City is the capital city of the Republic of the Commonwealth. It is named after Chancellor Sopot, the dictator of the Republic. it's likely either a new city that is built under Sopot or a city was renamed to Sopot's cult of personality.
The Commonwealth Civil War
During the Civil War, the Red Faction and Molov's squad attempts to kill Sopot in the Propaganda Building on Sopot City but escapes to the Citadel, after heavy fighting on the street between the rebels and the loyalists, Molov's squad manages to track Sopot into the Citadel, one of the Squad members known as Alias finally managed to corner and kill Sopot, after the Death of Sopot, Crate Molov takes control of the Commonwealth and declares the Red Faction a terrorist organization including Squad members Alias and Tangier.
After they escaped, Alias and Tangier help the weakened and leaderless Red Faction fight the remaining Commonwealth forces and discover Molov's plan to create new NanoTech-enhanced soldiers to conquer the world, after they located the Nanotech base below Sopot's statue, Alias made his way trough Molov's soldier and kills off Repta, after following Molov trought the Lab, Shrike betrays Molov and stole the Nanotech Cell from him and escaped, eventually Alias and Molov fought and Alias ends killing him before the Statue above the base could collapse, he is rescued by Shrike in his Aircraft.