I found your game neat and with good potential, but lacking in a few areas. Of course, I don't know exactly where you wish to take the game, but below are some ideas I hope might interest you. I have sorted them in approximate order of significance.
Feedback: More Strategic Choices
In my opinion, more strategic choices would make the game more enjoyable - presently the game has a few such choices, but it could have more. Giving the player tradeoffs where there is no one strategy to use can make the game more engaging and replayable. Further, if the player can craft cities that "feel" different, it can be more interesting (ex a large poor city, a varied city, a city focused on the rich, etc)
Layout: How you layout your city is strategic at first, but once you discover a good one, there's not really many more choices to be had - I feel there's only 1 good strategy to use. (A way to increase the difficulty of finding a good layout would be by making varied terrain, see suggestion below.)
Unlocks: I would expect unlocks to provide strategic choice, but there isn't much depth to them at current. ex, many of the unlocks are compulsory-build: I don't think a city can survive without police stations, fire stations, or landfills (I don't think there's a situation in which you'd have a reason not to build them). Due to the housing mechanic, you have to build all types of residences (though you can treat them all the same otherwise, other than needing more factories/etc in the same area to compensate for the higher density). Shops give a bit of choice -- markets give the most profit per resident (even factoring in the road cost), but have the least capacity/range, so sometimes it's more convenient to build the shops. As far as I can tell, office buildings are always better than factories (though I haven't experimented to see if a small number of factories is beneficial - even if that's the case, it's not a strategic choice, just a matter of optimization).
The Factory/Demand/Pricing system doesn't seem to have much choice on its own, though you do have to decide how much time you spend optimizing it vs building your city.
The click effectiveness upgrade could be strategic, except the economy is so difficult to get going and the upgrade so small that I can't imagine being able to afford them for quite a while. (However, I used macros, so maybe the player's time saved makes it worth it.) This ties in with my first suggestion:
Suggestion: Construction Companies
I was watching nanaki254's gameplay from https://itch.io/t/78870/my-lets-play-of-this-game, which reminded me of playing Cookie Clicker - this revealed what this game is missing: progression to alleviate the number of clicks you have to perform. Without this, I suspect the "clicking" aspect quickly becomes boring or even a nuisance (obviously it doesn't take skill to click repeatedly, just lots of time and a good wrist -- or a clicking macro).
To recreate this feeling of progression, you could add a series of "construction company" buildings that give citizens work to do, assist the player in construction, and cost the player the daily wages of those citizens. (An optional feature would be to allow closing down some or all construction companies without demolition in exchange for having a "hiring fee" when you want to open them up again). Thus, the player could invest in these companies to trade some profit in exchange for helping their city expand faster.
Construction companies could be of different tiers/capabilities (just like there are 3 different residences/shops). Larger companies could be more expensive to construct, hire lots more employees, and be a bit less efficient (per employee) than the smaller ones. To offset this, smaller companies should have a smaller operating range.
Every construction company should have an operating range, outside of which they cannot help - or, if desired, perhaps they can only help 25% up to a range of twice their stated range, and 0% after that. Unless bigger construction companies also have better quality (see "Building Quality"), a maximum range is the only reason one wouldn't want to spam the lowest quality buildings. An alternative could be that multiple construction companies cannot work together on a single building as efficiently as if they were doing it solo (do to extra communication). This would mean that each company would strive to work on a building that no other company is constructing; if none are available, it would help out with whatever it could at a penalty based on the number of companies already working there. ex, if 2 companies work together and each can contribute 0.5 clicks per day, maybe together they can only do 0.9 clicks. The more companies there are, the worse the penalty should be (though care should be taken to make sure that, for instance, a 10th company working together won't decrease the productivity compared to 9 companies).
Sub-Suggestion: Higher tech buildings cost a lot more
(This suggestion requires construction companies and takes away strategic choice in exchange for a feeling of increasing power.) The idea is that the first buildings the player is given cost even less clicks than they do now, but higher tech buildings cost tons more. Naturally there should be plenty of in between -- ex, some things maybe require 5 clicks, others 20, others 50, others 100-200, and some extreme ones maybe even in the thousands (though if construction companies are made to help with 100s of clicks/day, then naturally you could increase the cost of some special building(s) to 10k or more). The player would pretty much need to use construction companies to get the higher tiered buildings in a reasonable amount of time (though how many companies would still be strategic), but since it wouldn't be easy to make the big buildings on your own without companies, you would get a sense of power/progression when eventually you can build them quickly.
Sub-Suggestion: Easier Construction Tools
It would be nice to be able to paint buildings or shift+click to place multiple, to save player time. This would be nice even if construction companies aren't implemented (the idea being that you could finish construction later).
Suggestion: Simpler Profitable Start
In the currently released version, it's very difficult to break even (when starting out), much less make a profit in a reasonable amount of time. You can, but you need a long list of buildings (2 markets, 1 factory, 1 reservoir, 10 houses, and parks in a place that reach all the houses). Especially if you want to use the progression of construction companies, I would recommend a smaller list be required (though if the player has enough funds to be able to build construction companies to start with, the large list might not be so bad).
To do this, you might have an extra low tier, each with low cost and click count. ex, you might have a market stall that services just 6 or 9 people and has a very low range; there'd probably need to be a simple factory-like building too; you could also offer a well for water (also very low range). If you implement quality, they would be of the lowest quality. They would need to be balanced so that you can get a solid profit, given the investment. Ideally players wouldn't be able to spam such buildings everywhere and still make a great profit. I believe this won't be a problem due to their low range and capacity meaning that for the same number of residents you need to place a lot of them, which means you need a lot more police and fire stations. (If they have low quality, that is another limiting factor). If it is too easy to make a profit off of spamming such buildings, making fire/police stations more expensive could ensure it isn't the best strategy. After the player has the most basic profitable setup, they should hopefully be able to afford a construction company.
Suggestion: Rent Adjustment Tools
It would be handy to have a tool that you could apply in an area (maybe even a customizable area -- ex, you could choose whether to paint its effect in a 1x1, 2x2, 3x3, etc) that would automatically maximize the rent while striving for a given quality. ex, if the player specified a 2 star rating, the tool would get the highest rent that would maintain that rating.
Regardless of if the previous tool exists, it would also be nice to have a view that shows you the current rent of all residences, allowing you to see if you've missed adjusting one and/or to see how good the conditions are around each building.
- Water tiles (can bridge over them) - needed for certain types of water buildings; cannot put houses on them [I see you have this on your list of future features]
- Occasional ores; can benefit from placing mines on them (either straight money bonus or part of production chain)
- Mountain tiles that you can't do anything with (maybe can build a tunnel through them) (no need for this if water tiles aren't used by water buildings)
With these tiles spread randomly throughout the city, the player cannot rely on a "perfect layout" in all locations.
Sub-Suggestion: Vision Upgrade
The player doesn't get to see very far, but at the moment there's no reason to. If terrain is implemented, it would be advantageous to know ahead of time what an area is going to look like. You could spend money in exchange for all buildings having a larger sight radius. Possibly the starting sight radius is 1 less than it is currently
Suggestion: Poor/Rich Distribution Not Based on House Quality
At the moment, if you make sure that all your houses have 3 stars, there are almost no poor people in your city. But if you have a city of 1 star houses and add in a bunch of parks, this wouldn't (in real life) make them rich! Instead, perhaps how rich someone is should depend on other factors that are more difficult to influence, especially without losing profit (with the idea being that if you invest in the economy, your citizens might gradually become more wealthy, and then pay more taxes, making it a valid long-term option):
- Keep unemployment low/non-existent
- Keep health high (see below)
- High-tech industry/business (which may itself require good education)
- Low or reasonable prices.
- Crime (which could also be variable instead of "yes/no"; paying more per day on police stations or having multiple police stations could help counter-act crime)
You could have it so how rich someone is depends on how much they spend on luxury goods - you take their wage (dependent on being employed, quality of employment, health multiplier, and innate skill multiplier (since you don't want all the citizens to be making the same amount of money even if they all work at the same place)), then:
- if they can't afford rent and can't move to a cheaper place, they're homeless (if you're interested in implementing homeless; maybe homeless could increase crime rate if ordinances aren't in place to help them?)
- if they can't afford food, they're hungry/starving (health penalty) or homeless
- if they can't afford all the basic goods they want, they're poor
- otherwise they can afford 0+ luxury goods; if they can only afford some of these, then they're middle
- otherwise they can afford lots of luxury goods and they're rich (up to some limit (the limit should be in units, not dollars, especially if you take the Quality suggestion below)
- possibly, when the above says "homeless/poor/middle/rich", it should mean "the citizen progresses towards that state". ex, a citizen who has for the last month purchased all the luxury goods desired doesn't suddenly become poor because the price of food or basic goods skyrocketed. The value of a gradual transition would be to make it so that if you invest in hospitals, your population doesn't immediately become better at working, which would make them rich and give you more profit.
If you take this part of the suggestion, it'd be nice to have indicators to let the player know if citizens are struggling with the price of food/basic goods; alternatively, an estimate of how many can afford each type of good might be useful.
It would add another layer of complexity if certain buildings lowered the nearby or town-wide health. Anything that pollutes (certain types of factories, power stations, and maybe other things) could lower health. Parks and trees could help reduce pollution. (Parks might also increase health up to some limit simply as a place to encourage people to go outside). Hospitals could also raise health regardless of pollution levels (to some limit). As mentioned, health could impact how rich the population is (in real life if everyone's sick they can't work nearly as well), possibly via wage income (as in previous suggestion) - or, if not, you could have it impact overall taxation rate (ex good health might mean +10% taxes, or at least bad health might mean -10%).
Currently, a rich person doesn't care where he/she works/shops, but in real life the wealthy tend to prefer (and can afford) higher quality establishments and products. If the player has a population of rich people, it would make sense to be able to build higher quality shops (in the area where the rich people live, anyway) to get an increased profit -- the problem for the player would be that poor people would avoid these shops simply because they couldn't afford the increase. Such shops would only be able to have the "high quality" bonus if they're stocked from high quality factories, which themselves might only work (or work well) if there's a well educated population.
Buildings with higher quality potential would naturally cost more money and clicks to build, and may have a higher maintenance cost. Possibly, a low quality construction company cannot build medium quality buildings (with exception to medium (and maybe high) quality construction companies).
Minor Feedback: Residential rent doesn't make sense to me
At least for the large residential buildings, my impression is that you collect the same amount of rent regardless of how many people are in it (unless it's empty), but I would expect that it should be multiplied by the number of apartments in use (ex maybe 3 people in each apartment)? To offset the potentially increased profit, perhaps the larger buildings could have a lower base rating (since apartments are less desirable than having an entire house to yourself, unless the apartment is cheaper).
Minor Suggestion: Markets/Shops Provide Employment Opportunities
I think it would make sense - obviously people need to maintain the shop - though if you're wanting to keep the interface simple then it might clutter it too much (unless you made "residences and employment" and "residences and shopping" views). If you implemented it so that the shop doesn't work without employees, I'd hope that there'd be a priority system so that shop jobs shops could steal from less important jobs (like factories). If shop employees were implemented, it would give a reason for the daily cost already given to the shops.
If you find any of these ideas useful, I'd be glad to hear it!