Zones, floors and the people in them

The one-minute explanation

Zones are the only things that consume development capacity, so they are where the city’s design decisions actually cost something. Every zone carries the same small set of choices: what it is, what shape it takes, how tall it is, and what it is called.

Two rules govern everything downstream:

The eighteen kinds

Zones come in four families, plus water which lives with the terrain tools:

Several kinds carry a demand subtype — commerce has nine, education seven, civic and medical five each — which is what lets the capacity bars in Reading your city break a full category down into what actually filled it. Kinds without subtypes are deliberately aggregate.

Drawing a zone

Pick a kind, pick a shape — rectangle, circle, triangle or pentagon — and place it. A short drag stamps the kind’s default footprint, which is sized for what it is: a station arrives at 120 × 60 m, an airside area at 800 × 500. A longer drag sizes the zone as you go.

Afterwards the shape is fully editable: drag the body to move it, drag anchors to reshape or rotate, hold to scale uniformly, pull the square handles to bow an edge into a curve, double-click an edge to add a point, right-click to remove one. Holding the modifier while dragging pulls out a copy rather than moving the original — the fastest way to lay a row of similar blocks.

A zone may also carry a courtyard: a hole cut through it. The hole is excluded from floor area, so a perimeter block costs you less allowance than the solid slab of the same outline — and looks like a city rather than a warehouse.

Filling whole blocks with the Zoning tool

Drawing every block of a big city by hand is possible but tedious, so the dock carries a Zoning tool that fills a whole street block with buildings in one press. It is strictly a shortcut: everything it places is an ordinary zone you could have drawn yourself — select it, reshape it, restyle it or delete it afterwards — and one press of Place Buildings is a single undo step.

Click inside a block that roads enclose. The tool reads the road network itself, so a block only exists once its streets form a closed loop; a dead end or a gap leaves nothing to pick, and the hint says so. The Selection extent controls take you up and down the scale: Grow merges in the neighbouring loops so a super-block of several small blocks fills in one go — the inner streets survive as block boundaries, each block filled on its own — and Shrink returns towards the smallest loop.

The card is where you decide the district's character before anything is placed:

• Land-use mix — a wheel of five sectors: residential, commercial, office, industry and public service. Drag the handle between two sectors to shift share from one to the other. Shares set the proportion of plots each use gets, not the amount — how much the city may build in total is still the development capacity decided on the macro map.
• Total floor area — one slider; floor counts are derived from it, so the same fabric can be a low-rise quarter or a dense one.
• Density — how tightly buildings pack. At the top nothing is held back and buildings sit almost wall to wall, Manhattan-style; at the bottom a quarter of the plots stay open.
• Will add — the public facilities this block is genuinely short of. Their number comes from population thresholds and their position from service radius, both measured against the whole city, so most blocks add none: a city needs a few hospitals, not one per block.
• Parking — buildings absorb their own parking first; surface car parks appear only for the remainder, so the denser you build, the fewer you see.

Buildings sit back from the kerb and only rise within about 80 m of a street, so drawing more local streets into a large block is what raises its buildable share.

Two things the tool never does, by design. It never draws roads, rail, transit lines, stations, terminals or airfields — transport stays yours. And it never places parks, plazas, sports grounds or heritage — the open share it leaves is exactly where those go, and they are how a district stops looking generated.

Floors decide what you built

Every building kind has its own floor range and its own default, and those ranges encode what the kind is:

Industry stops at six floors and heritage at five because factories and temples are not towers. Only housing and offices reach 120.

Adding floors spends allowance exactly as spreading out does — a twelve-storey block on a small footprint and a three-storey block on four times the ground cost the same. What differs is the land they leave over, and what the building becomes.

Housing changes character as it rises

Residential floor count is not just a multiplier; it decides the kind of housing you built, and with it the assumed home size:

The consequence is worth pausing on: the same residential allowance houses very different numbers of people depending on how you spend it. Villas at 250 m² per home put a fraction of the residents on the same floor area as mid-rise flats at 95. If you want a dense city, the density is a design decision made in the floor field, not a setting elsewhere.

You can override the assumed home size per zone when a district should be more or less generous than its band.

Mixed use splits the bill

A mixed-use zone declares what proportion of it is residential and which non-residential uses fill the rest — commerce, office or industry. Its floor area is then split across those uses and charged to each category separately.

That makes mixed use the tool for a category that is nearly full: a district that cannot take another pure commercial block may still take a mixed one, because only part of it lands on the commercial allowance. Changing the split later re-checks the caps, and can be refused for exactly that reason.

Naming and grouping

Every zone can carry a name, shown always, automatically by zoom, or never. Beyond that, zones can share a group name — and a group is treated as one navigable place. A campus of eight buildings, a housing estate, an industrial park: give them one group name and the city treats them as a single destination in search and in the manager, rather than eight anonymous polygons.

This is the cheapest way to make a large city legible to yourself six sessions later.

Who ends up inside

A building is not empty once placed. Every building zone gets an occupant roster — companies, institutions and merchants — generated deterministically from the world seed, the metro and the building itself, so the same building always holds the same tenants and no two players' cities read alike.

The roster distinguishes chains from independents, gives each occupant a monogram until you supply a logo, and rolls an importance level from 1 to 5 that is gated by the building's height and the city's own facts — a village shopfront cannot roll a national headquarters.

You are not stuck with what it generates. You can add your own entities, delete the automatic ones, rewrite names and descriptions, and upload logos; deletions are remembered so a regeneration will not bring back what you removed.

The level-5 slots are national

Level 5 is never rolled. It is allocated nationally, and the rules are worth knowing because they are a genuine reward for growing cities:

• The nation gets one slot per three million people, minimum one, capped at five.
• Slots go to the largest metros by population, with the capital's metro first.
• Within a metro, the slot lands in the flagship office building — the office zone with the greatest floor area.

That last rule has a consequence players discover by accident: build a bigger office tower and the flagship moves to it, taking the level-5 occupant with it. The prestige tenant follows your architecture rather than sitting where it first appeared.

Practical habits

1. Check the bar before drawing the district, not after. The refusal fires on placement, on floor changes and on mixed-use edits; knowing which category is tight decides what you draw.
2. Spend height where it buys density. Residential floors change the form and the home size, so the same allowance can house a suburb or a city.
3. Use courtyards. A hole reduces floor area while improving the block — it is the one edit that makes a city both cheaper in allowance and better looking.
4. Reach for mixed use when a category is full. Splitting the bill across two allowances is often the only way to keep building in a mature district.
5. Group things as you go. Naming a campus once is far easier than identifying eight buildings later.

Common misconceptions

“Building tall saves allowance”

It does not. Floor area is footprint times floors, so height and spread cost the same. Height saves land, which is a different scarce thing.

“I can stack parks to boost green space”

Land uses are counted as unioned ground area. Overlapping shapes are counted once.

“Residential capacity determines my population”

Population comes from the national simulation, not from what you zone. What your housing choices change is the form of the city and how much allowance a given number of homes consumes.

“The tenants are random”

They are deterministic from the seed and the building, and level 5 is not rolled at all — it is assigned to a limited number of national slots and sits in each metro's largest office building.

Continue the collection

Next: the streets that have to reach all of this — five classes, each a complete cross-section, and the corridors they form.