Ok, while the game is great and production queue is not the biggest concern right now, I've been thinking about something that can, IMHO, make the game better. So without further ado, here's a proposed Infrastructure production rework:

1) Original problem

There are too many infrastructures. When choosing them, especially on a newer city, its hard to have a 20+ items list to choose from. A new player can be overwhelmed by the sheer number of choices available and its hard to do a comparison on what to build next, not to mention it is strange to keep building things from a very early era. You don't see modern cities building aqueducts, for example. In addition, you build too fast as production is becoming huge. 

2) Proposed Change 1
Remove from the buildable list all infrastructure that wont change your city. If you have no River tiles in that city's territory (and any other attached territories), then remove the Flood Irrigation infrastructure from that city buildable list. If the city has no Harbor, then remove the Fishmonger; if it has no horse or farmer's quarter, remove the animal barns, so on and so forth.

3) Proposed Change 2

I suggest that newer infrastructure obsolete older ones. This should mean that both their production costs and effects should be increased ( For example, when you research Playhouse, you can't build the Theater anymore, and whenever you build a Playhouse it overwrites the city's Theater, but the Playhouse gives +4 influence instead of +2 and has increased Production cost). In a sense, when you're building the newer infrastructure, you'll be building simultaneously each and every other infrastructure behind it on its upgrade line. Another example should be the Coal Power line - once you research High Furnace, you can't build Charcoal Kilns anymore (and Charcoal Kilns already had obsoleted the Forge), but the High furnace should give the bonuses of both High Furnace, Charcoal Kilns and Forge combined. Those two changes should reduce the number of available infrastructure to build and make it easier to decide what to build, but create another problem:

4) The new problem - and its solution
I fully understand that increasing the infrastructure costs by absorbing its earlier counterparts presents a new problem. New cities, with its lower production values, will have a hard time building this new buildings. For that, I propose a change that opens up new design space for cultures' LT, EQ and EU = removing the distinction between shared projects and normal buildings. HK already does a wonderful job on shared projects, and my suggestion is to end the "shared projects" category and allow any city to send its production to any other city on your empire to help with building anything you want. You can implement a penalty for sending production, based on the distance between the cities, which can be reduced by techs, civics, and culture's LT/EQ/EU. If you want to go deeper, these production trains can spawn automated units that travel between your cities and can be plundered by an enemy, so that is even more design space for interactions. This should mean that if you want to have new cities with meaningful infrastructures, you'll need to either wait, use the Settler units or send production over from your more established cities.

Hope you enjoyed this little suggestion and happy 2021 for everyone!

docktorkain wrote:
Remove from the buildable list all infrastructure that wont change your city. If you have no River tiles in that city's territory (and any other attached territories), then remove the Flood Irrigation infrastructure from that city buildable list. If the city has no Harbor, then remove the Fishmonger; if it has no horse or farmer's quarter, remove the animal barns, so on and so forth.

Second this. Some of the infrastructures doesn't make sense considering the actual terrain they are in.

I would like to agree to all of your proposed ideas, except the last one. I already thought about similar changes. And I think the game absolute needs this changes. I've been playing since Civ1 and found it very annoying that the game offers me things that don't make sense in a certain city. Change 2 I already missed in Civ but in HK it is much more critical, because of much more choice.

The last one (point 4) is to complex, I think. But I like the idea of shared build queues (shared projects) or maybe one of the following: 

• I think the settler unit, you can build later on, is match simpler solution, and it is also easier to understand. Maybe it's easier to use this "build in feature" to build and send settlers with some basic infrastructure stock (which is also already build in, but adjust further it)? This infrastructure stock (districts) you can set on tiles you want (e.g. you can set up 2 infrastructure projects, 2 workshops and 2 farms much cheaper or free, but they need some time to go online...).
• Perhaps all neighbouring provinces can support this new settlement (like neighbouring bonus of all districts)? Or only city built this settler?