Thousands of kilometers away, near a wide underground rift.
Black smoke swirls, gears roar.
Tens of thousands of machine puppets are busily working, continuously transporting wood, coal, and other materials into the warehouse.
The mechanical cores of these puppets still bear the shadow of the Fire Source Civilization's technology, naturally utilizing the crucial knowledge that humans had initially traded away.
Since Green Grass City embarked on a new journey, the Underground Alliance has grown at an unprecedented pace, and has now essentially digested the technology traded by humans.
"I announce, the first test voyage of the Underground Alliance's Sky City, officially begins!"
With the command, the entire ground emitted a slight tremor, and the city "boom" lifted off the ground, slowly rising like a hot air balloon.
"Report to the Governor! City's operational status, normal."
"All generator units, normal!"
"Current altitude, 300 meters...500 meters...1000 meters."
