Population fluctuation since I reached 500k is first inexpiable/without reason and second in the tens of thousands.
I know there will be some who post here that the reason for this is my traffic or roads or this or that and they themselves have yet to get past the 250k population mark. The game you play at a sub 250k population is nothing like the game from 400k and beyond.
What I experienced and the issues I had when I had 70k pop & then 120k pop & again 230k pop pales in comparison to what happens when one reaches beyond 400k. I would lose 2k per week then two weeks later I'm losing 4k in pop then a week later only losing 1k then two weeks later 6k a week after that 8k to 3k etc. etc. etc. all the way up to 10k in pop then back down to 1k. Then for no reason, no changes on my part, nothing happening my population is growing by thousands and thousands per week again.
I went from 530k to 480k back to 520k to 490k to 570k to 520k etc. etc. etc.
I'm currently at 680k and it is so frustrating and UN-FUN bordering on painful to get to this level. I've bounced from 660k to 680k ALL DAY TODAY! A 10 hour play day!
Like I said I had to give up on my first 500k city because I just lost interest due to the fact that the population fluctuations are so massive and so very quick to happen. For no reason at all (no lack of water or sewer or education or jobs or commercial or mass transit etc.) the population fluxes are just unworldly.
According to Steam I have logged in more than 290 or so hours now and I can fix most issues, understand how the game mechanics work, the ebbs and flows but once that 400k/500k population mark is reached all logic goes out the window and the struggle to understand what is happening is simply not there.
I'm not bragging or trying to show off in any manner. It is obvious (to at least me) I know what I am doing and how to do it. I've logged the hours. I've done it all twice now yet it is just getting less and less fun the longer a city survives. At least for me.
Where is tourism? At one point I was spending more than $20k per week in tourism; airports, parks, buildings, assets etc. and the most amount of tourists I had in the city at one time was 154. It makes no fiscal sense to even attempt tourism. It did not work when I had 75k population it is even more devastating when the population rises and rises. Planes arriving and taking off with zero cims.
IMHO, the devs have a lot and I mean a lot to flush out of this game to make it run properly at all levels of population. I read so many posts here from folks and they post that they have 25k or 45k or 18k those issues may very well multiple by thousands if not tens of thousands like it did me. Then who does one turn to? I'm supposed to ask someone who has a population of 25k who has logged 38 hours for answers?
My opinion is after one reaches 400k population then 500k pop then 600k pop should there really be any questions/issues that can't be explained/solved?
My opinion is after one reaches 75 hours of play, then 150 hours of play then 225 hours then 290 hours of play; should there really be questions/issues that can't be explained/solved?