Night City, Happy At Last?

All in all, by 2020, Night City had evolved into a busy, successful, and dangerous urban zone. The government managed to keep the lid on, and when they failed the Corps could be depended on to re-screw the lid down with their own brand of violent and implacable savagery. Deals got made, money changed hands, some people got killed, but other people managed to avoid getting killed in turn. Night City wasn't the utopian city of Richard Night's futurist dreams, but in the main, Night City in 2020 worked. 
Then came the 4th Corporate War.

Night City and The 4th (2022)

The full story of Night City in the 4th Corporate War has, by now, been the subject of many dozens of books, movies, and even a few braindances (recorded from captured fighters under extreme duress). What's more important is Night City's unique position in the chaotic, unstable world of the early 2020s.
Because of its Free State status, Night City was home to units on both sides of the 4th Corporate War. The War was not kind to Night City. There was constant street-to-street, building-to-building fighting throughout the City, especially around the Corporate Zone where both factions maintained substantial office complexes. Even before the nuclear event that wiped out the entire area, people were abandoning the city in droves, doing whatever they could do to avoid getting sniped by drones, crushed by tanks, or just gunned down by Corporate kill squads. A big chunk of the City was wrecked, and people were climbing all over themselves to get to safer spots like Heywood and Pacifica.
Then both sides went over the line and come bright boy dropped a bomb.

The Bomb (2023)

In retrospect, it was just Night City's bad luck that it was a Free City in an area not controlled by a larger power like a nation. Neither of the Corporate combatants was stupid enough to drop a nuke in the middle of some place where the remnant U.S. or the still powerful EuroTheatre cared about. In fact, probably the only thing that kept then-President Kress form wiping out every Arasaka stronghold on earth was the fact that Night City wasn't technically part of the U.S. 
So, they dropped a bomb.
The power of the bomb detonated in the Arasaka Towers was about a tiny fraction of the Hiroshima bomb; basically a tactical nuke a bit larger than a "suitcase bomb;" it was designed to utterly demolish Arasaka's Reliquary Database Project and make it unusable to a rival Megacorp. Similar to a 1950s Davy Crockett backpack nuke, with an overall yield of .1 kiloton, the Nuke was prematurely detonated at floor 120 (366m/yds), in Kei Arasaka's apartment bunker where the Soulkiller lab was located.
The blast instantly obliterated the Arasaka Towers, splitting them in half and causing them to collapse outward. The entire central city became rubble in seconds with almost everyone in the immediate area dying instantly. And, as much of Night City was built on fill, because the elevation (5m/yds) was originally so low, the Arasaka nuke caused a minor earthquake that liquified parts of the fill and flooded the inner city.