((We're in a comicbook multiverse. Reed Richards is not useless, i.e., the tech level is stratospheric (but most of the world is playing catch-up), and to be competitive in the business world requires either superpowers or Batman-like foresight.))
((Also, we're starting at the end and ending at the beginning. I was going to do this whole OOC accordingly, but eventually thought better of it. Someone please explain how this box got here. Introducing characters who'll be relevant earlier is optional, but probably good.))
The city unpacked from a single grey box. The lid flipped open, and a box of equal size tumbled out. There were two, and then four...
There was a taproot-like center, and branches running all along the ground, cast in search of resources.The ocean hung overhead, and the light danced in interference patterns, cast as it was through the surface's waves.
Like a blade of grass, the first hose rose to drink from it, and thousands followed. Water filled the city's storage tanks and spherical ponds. Synthesis centers began to ship in raw matter via maglev rail, and set about inducing abiogenesis.
This would be the fast part; evolution, the slow.