First, I said sometime before that I would further illustrate CuRB, but unfortunately the video card I had in my computer (which I used to replace a dying video card) died, so I’ve resorted to using my laptop. I still want to explain CuRB later on, but showing those customised setups may already give you a general idea how CuRB can go. By the way, that last setup I showed was for an angled parking lot; that one was optimised to have as much parking as possible; a more basic version would be exactly like how the NAM’s SAM-1 works except it’s functional and not eyecandy. Now on to the rest of the comment.
I recently pitched the idea about unlocking a steam locomotive by restoring it and getting a historical boost to your city as a result. Well, based off of feedback (IE, what other boost having a steam loco could have), I’ve refined the idea:
A nearby city has offered you one of its last remaining steam locomotives to your city. You can choose to:
Scrap it - You get a large chunk of cash for doing so but at the expense of historical value.
Put it on outside display - You get a small boost in historical value but a small vandalism risk. There is a small fee for building the park, which has an upkeep cost.
Build a railway museum - You get a large boost in historical value and a small boost in education. There is a large fee for building the museum, which has an upkeep cost.
Restore the locomotive to its former glory. You get a large boost in historical value and tourism. There is a very large fee for restoring the locomotive and constructing a new shed for it, both of which have upkeep costs.
I do have a simpler example, which could look like this:
One of your city’s oldest school buildings is now recognized as a historical building and your local historical society wants to convert it into a museum. Completing this task will grant a permanent historical and education boost to your city. You can choose to:
Convert the building.
Leave building as is.
Note: Only one school in your city will ever be made into a museum, or an advanced version of this task can pick a random building, like a fire station (which would give a fire safety bonus instead of an education bonus).
These special tasks aren't actually the topic I wanna discuss; it's the fact that we have vehicles and buildings that serve more than one purpose, or rather, have a primary and one or more secondary purposes. This gets into my next topic, which I'll show like this:
Residential + Commercial = RC Mix
Industry + Education = Trade school?
University + Health = Disease research
Industry + Health = KC's equivalent to OSHA
Residential + College + Other stuff...? = University
Education + Law enforcement = Police academy?
University + Transportation = Traffic engineering (Unlocks road micromanagement?)
University + City administration = Civil engineering (Unlocks more micromanagement?)
Instead of features being unlocked that have multiple purposes, I propose something like this for unlocking progressively more advanced city features: having a certain amount of whatever you needed unlocks the building or feature. (Fun fact: I commented in my notes that this presentation of combinations was basically a city-builder based off of Doodle God, Little Alchemy, and Elemental 3; if you know what the last one is, half of the game is combining elements with themselves and suddenly realising you have 9223372036854775808 ceramic vessels. The concept is tempting, I will say.)
Obviously, this method of unlocking things is self-explanatory; In SC4, I believe you needed a certain population threshold to be able to use medium and high-density zoning effectively; ideally, those zone levels would be locked behind a population threshold, but they're never locked so you can just zone using whatever and potentially make a costly mistake. C:S locks most things behind population thresholds, but some other things are locked behind having X amount of something. I just want to elaborate on a few examples.
Education, for example, would unlock buildings of progressively higher education levels; elementary school unlocks high school, which unlocks community college, which unlocks university, which unlocks even more options such as disease research (though this requires health buildings). University, in particular, is an insanely complex piece of machinery, and I say this being a university student already. You need apartment complexes for students to live in if they don't go for on-campus housing, you need stores for them to buy groceries from, restaurants for them to eat from, sufficiently large roads to handle all the traffic, some form of transportation system for those who don't have cars, and so on, and that's on top of having all the other levels of education already. I know there's nothing that would simulate individual citizens coming and going (and yes, I know that education systems are different all over the world), but a simplified requirement list could go something like this:
X amount of high-density residential
X amount of stores
A bus line
All previous levels of education
Power generation would start off with simple methods, such as coal and natural gas. Green energy such as wind and solar doesn't come in until later; green energy should also be weak at first but can be made better with progressively better generations and energy storage; these methods will require high-tech manufacturing (which, of course, requires higher education) and solar panels in particular can also be installed on top of almost anything (so that's electricity plus everything that's a building or house). Here's a case where you don't upgrade almost anything at all: if you luck out with having a really big river, you can power your city with hydroelectricity and have no need to upgrade your power gen beyond unlocking hydroelectricity, and if your generators are that good or you're really energy efficient, you can even sell the excess electricity to the rest of the universe (or Kotiverse in this case).
The biggest takeaway is that any one building type is not isolated from all the other building types. I hope I've explained enough.