One feature in the game which I don't partiularly like is the way in which the empire's appearance changes between the industrial to the contemporary era, so I gave some thought as to how this could be improved.
I don't like this mainly because it is an immersion killer, but also, it just makes the game look visually so much worse and, relatively speaking - unrealistic. What I mean by this is, every building in the world is not a midrise or a highrise, the vast majority look almost no different to industrial era buildings. infact, many districts of modern cites still have huge areas of pre industrial architecture. Granted - the world has changed radically in a short period of history, but most countries either don't have skyscrapers, or have just a few in select large cities. In HK, going era V to VI is like seing Tokyo appear overnight. This could be fixed by the following change; when transitioning to era VI, building style doesn't change, however, buidling a new district in the contemporary era, you can select it as an era V or VI version, the era V version would have one bonus, (either influence, stability or fame) and appear in the era V style. The era VI version however, could have a % yield bonus and appear with the era VI appearence. There could also be an upgrade district buildable that for a reduced production cost, modernises a tile, giving it the % yield bonus. This would make city growth seem more natural, and improve the visual progression of the game. On this note, and please bear in mind I say this as someone who absolutely loves the artstyle and appearence of HK generally, the era VI building assests could be made so much nicer.

A similar issue I have with city building is the way the fortification infrastructures work - which is, nothing like real world cities. Westminster doesn't order the extension of basions around new council estates being built on the outskirts of london. At the extreme end, in HK there is practically entire continents of modern city behind walls. Historically, walled cities typically only wall the city centre, where there is food storage for surviving a siege, and ample room to condense troops into a deadly fighting force. Therefore, I suggest that the infrastructure fortifications only build walls around the city centre or administrative centre tile, and the combat system be altered to allow multiple units (maybe 3) to operate from this tile during a siege. Additionally, walls become a building contructable whereby you can select specific tile edges to build along to you can wall off around particular geographical features tactically. This creates an interesting gameplay descision - how big do you build your walls, will you need to expand them later? etc... This would also simulate the outer and inner walls of a city during combat. each tile edge you select for the construction project adds a production cost. This would go a long way to imrove the realisim of war and sieges around cities by way of making city placement and planning far more tactical and strategic. The attacking team would have first breach the outer walls, then burnout the well defended city centre reserves to capture. This would also further improve the appearence of cities, since they wouldn't have an emphasised weird hexegonal shape. Something else that could work in tandem with this change would be a general buff to the defensive bonus of being on a district.

Something that does bug me a bit in HK compared to other games is the persistance of district spam - that is, the dominance of placing huge amounts of one district type for adjacency bonuses, I think the game would be far more interesting if there was an way to play that provided some benefit other than stability for not building a makers quarter on every tile. By suggestion for this is that national parks should be buffed to provide fame as well as influence and negative pollution (bonus fame for being built on a natural wonder. They should be larger in size, being 10-15 adjacent tiles which can be selected by the player. This would incentivise leaving areas untouched. Another way in which to avoid district spam would be to buff tile improvements by having cheap early game infrastructure specific to said improvements eg. + 20 production on clay and dimension stones, +10 food on marsh and berry bushes, +20 science on crater and hot springs. Alternatively, these could be incorporated into existing infrastructure, like stoneworks, flood irrigation and school. Late game infrastructure could make these bonuses even larger. Also by removing the yield of the tile when a district is built upon it, there is a trade to building over these high yield tiles.
The last idea I have regarding an alternative to district spam, is to have an improved farmers quater, or a farmers hamlet, perhaps it could be called 'agricultural village'. it could be placed like a hamlet, but it exploits only food with a 2 tile range. Late game infrastructure or even the narrative event about studying crops could add other yields to it eg. +1 science on tile producing food exploited by agricultural village. These additions would simply give an alternative way to play, maybe not better in all situations, but certainly some, and variety of playstyles is something this game needs a bit more of in my opinion.

Anyway, Those are some of my thoughts on the games building mechanics, I know that they aren't fully fledged, but I think if implemented some way, they would go a long way towards making HK more interesting to play, and visually much more natural.

I think these ideas have been mentioned before by others. (ie they are good ideas that many players would like to see!)

My own simple additions:

1) Farmers quarters should stay 95% fields even into modern times. Because yes, farms in the modern world still look like fields, not a ton of skyskrapers.

2) I've also advocated that city walls either (a) just surround all the districts directly adjacent to the city center or (b) they must be manually built for each tile, so you can choose which tiles to defend, but if you want to defend alot, you must build alot.

3) This one, I think must stay the same. If we just have a rainbow patchwork of districts, you can't specialize each city which means every game would be the same. And it already kinda is... so we don't want to go more in that direction.

For the farmer quarters not being farms, I think the best solution would be something proposed very early on - making Makers and Farmers much more exploitation dependent and the other two adjacency dependent, so you'd replace quarters as the city grows and move industry/food outward. Not that it can really be done at this point, but I still think that much more emphasis should be put on exploitation rather than adjacency for Food/Industry, so just clustering them wouldn't be an answer (another thing would be a return of Quarter synergies).

I agree with your sentiments here. Lots of good ideas.

I'm just going to discuss one of them, although I think they are all interesting:

Hamlets (or some equivalent of, like free placement of farmers/makers) could come much earlier, resulting in a patchwork of small settlements (and early empires would be more vulnerable to raiding as a result). A lot of the DLC cultures, (plus the change to harbours) have been leaning this way already. 

This would also naturally reduce the size of the area protected by the city walls, until you start really expanding the city center. Historically this is around the time medieval city walls became ineffective against gunpowder. 

The Bastions infrastructure image is a star fort. A real star fort is approx. the same 'size' as a garrison, so maybe in this era we could start to see garrisons being replaced with star forts and being unable to be bypassed (maybe something along the line of what Ethiopia do?). Then in the modern era you have cities themselves being inherently defensible (Stalingrad etc.) at the cost of widespread destruction, so maybe each hex could be a separate 'wall', slowing attacker movement to a crawl. You would then really need artillery to take a city, with the associated destruction of districts. 

Also city defenders should get ranged weapons much earlier. 

DNLH wrote:

For the farmer quarters not being farms, I think the best solution would be something proposed very early on - making Makers and Farmers much more exploitation dependent and the other two adjacency dependent, so you'd replace quarters as the city grows and move industry/food outward. Not that it can really be done at this point, but I still think that much more emphasis should be put on exploitation rather than adjacency for Food/Industry, so just clustering them wouldn't be an answer (another thing would be a return of Quarter synergies).

I think this is already here subtly in the game, but it could be heightened.  In the Ancient-Medieval Eras, exploitation is more important than adjacency, so the location of of food and industry on the map is going to shape the initial growth of your city.  By the end of the Medieval through the contemporary eras, adjacency bonuses begin to shape your city more than exploitation, so your city's boroughs begin to grow out from existing districts with less care for the terrain. I think it's a neat, gradual growth.

I'd have loved to see more of that with the contemporary era and really wish Singapore's Communal Housing had exemplified this: Community Housing could have counted as a Famer, Market, and Research Quarter and benefitted from adjacency, but not exploited the terrain around them; they could be the dense urban cores while you continued to build farms on your outskirts.