In general, no, simply because district cost scaling puts players who cannot expand at a disadvantage.

I've suggested this to change it:

https://www.games2gether.com/amplitude-studios/humankind/forums/169-game-design-and-ideas/threads/48294-preventing-snowballing-global-district-count-scaling-cost?page=1#post-352401

I (loosely) tried once. I was transcending through all eras with the Zhou, so not the very best example!

I had a six-territories continent for myself (small map with roughly one continent per player), tried to make that only one city from start. My insight is one city doesn't generate enough population to generate enough influence to keep up with the influence cost inflation (claiming and attaching territories, civics, wonders - but good luck constructing the ones past the Ancient era with only one city), and gaining stars in each domain becomes more and more difficult, if not impossible.

Thankfully I was able to assimilate the rebel city of another AI to save my game.

I guess the best/fast to get it will be on Blitz with just 1 more AI, and try to conquer it.
That is my advice if you only want to get the achievement.

Daarkarrow wrote:

I guess the best/fast to get it will be on Blitz with just 1 more AI, and try to conquer it.
That is my advice if you only want to get the achievement.

I got the win with 1 city achievement by accident. I "won" the game by turn limit, while very much losing a war against every other civilization in the game. The turn limit happened to pop when I only had 1 city uncaptured by my enemies.

It's certainly doable. You don't have to play the entire campaign with only one city. (Unless this is actually what you want to achieve, of course. One-City campaign would still be possible as well, though, provided that you adjust game settings as facilitating as possible, like tiny map with min number of AI, preferably in archipelago-like map, etc.)

Achievement is unlocked if you have only one city when victory conditions are met. It might be considered as cheating but you can just combine all of your territories into one city at the end of your campaign just before victory is triggered. Stability and food shortage problems can also be overcome with careful planning and appropriate culture selection (Austro-Hungarians is a must, for instance) if you don't want to have downward spiralling city at the end of your game.

So, what's the victory condition you're aiming for? Please, do tell us later how your one-city story turns out to be.

I think the most crucial issue that one-and-only city will bring is stability rather than exponentially increasing building cost if you intend to build a metropolis with several territories. I'd personally start with Zhou or Egyptians and proceed as Carthaginians and Swahili later (provided I had enough coastline) for a strong economy since there will be a severe shortage in influence with only one city. If I could make it into Medieval with a robust economy I'd need less industry to build and less influence to claim/attach territories. Then I'd seal the deal with Mughals for industry power and some Gajnal action, Austro-Hungarians to eliminate the whole stability problem (with at least 10 territories) and Japanese for a quick closure to my journey.

I'm curious to know how your own journey will shape up.

P.S. I personally believe Harappans and all other agrarians are so overrated but this is another discussion for another post. Maybe, AI has finally learned to arrive at the same conclusion. :)