- You may be looking for the article on New Mobotropolis.
Mobotropolis is a city nestled in the Royal Hills Zone on Westside Island and ruled over by King Acorn. It was taken over by Dr. Eggman when he seized control of the island, but eventually liberated by the Knothole Freedom Fighters under Sonic the Hedgehog. Since then it has returned to its capital status and served as a home for the Freedom Fighters.
Threatened by Eggman
Mobotropolis was built on Westside Island, and eventually came to be ruled by King Acorn. After Dr. Eggman initiated his coup, he took over the city, but left it in its previous condition, something that Rotor saw when he arrived in the city. Years later, the Knothole Freedom Fighters would liberate the city from Eggman's clutches and restore King Acorn to the throne. However, his reign would briefly be interrupted when wizard Walter Naugus imprisoned him using technology stolen from Dr. Eggman. Fresh from the events of Worlds Collide, Sonic awoke in the middle of the city (on a rainy day) to discover the place was being attacked by the Tails Doll-which had arrived in pursuit of Naugus-and that he and Tails were already in the process of fighting it. After shaking off his confusion at why everything was different, Sonic successfully disabled the demented doll and kicked it over the horizon. (FCBD 2014, StH: #252)
Later on, the city was on attack again when Metal Sonic was on a mission to kill Sally Acorn. She was also accompanied by Cream, Amy Rose, Bean and Bark (though the latter two escaped because they were wanted criminals), who have just returned from their adventures in the Sol Zone. Sonic later came to the resuce to direct Metal Sonic away from the city, and because he had other urgent matters at hand, Tails, on the Tornado, fired a missile at Metal, though he survived the attack enough to fly back to the Death Egg. (StH: #256)