rci-demand mechanic sourced
RCI demand
A demand signal for residential, commercial, and industrial land derived from the balance of jobs, workers, and goods.
definition
Owns three demand valves (residential, commercial, industrial) updated from the balance of population, jobs, and outside trade, and read by zone growth. In Micropolis, the SimCity engine, projected residents = residents + migration (proportional to jobs per resident - 1) + 2% births; projected commerce = total population / 3.7 x a labor ratio capped at 1.3; projected industry = industry x labor ratio x an external market factor (1.2, 1.1, or 0.98 by difficulty). Each valve moves by (projected / actual - 1) x 600 plus a tax offset (+200 at 0% tax, 0 at 7%, -600 at 20% on easy), is clamped to +/-2000 (residential) or +/-1500, and is held at 0 until a needed stadium, seaport, or airport exists. A zone grows when valve + a local score (land value for homes) passes a random test. SimCity's RCI bar and Cities: Skylines' demand bars display these valves.
player experience
A steering signal. The player glances at three bars, zones whatever is in demand, and learns that homes need jobs, jobs need workers, and industry needs outside trade. When a bar stays pinned despite growth, the player hunts for the missing stadium, port, or tax cut.
design levers
- inputs to each valve (jobs per resident, internal market size, external trade, taxes)
- gain and clamp on each valve, which set how fast demand swings
- caps that hold demand at zero until a specific building is placed
- how much local factors (land value, traffic, pollution) add to the global valve
- whether demand is split further by wealth or density tier
failure modes
- Players treat the bar as an instruction and zone mechanically, so the city grows without plan or tradeoff.
- Hidden caps (needing a stadium or port) freeze growth with no explanation unless an advisor says why.
- High gain makes demand oscillate between booms and abandonment.
dynamics
- Residential and job growth chase each other, producing alternating waves of house and workplace construction.
- Raising taxes depresses all three valves at once, so tax policy shows up as slower development rather than a direct penalty.
- Valve caps create milestone moments when one building unlocks a growth spurt.
open questions
- Would demand derived bottom-up from simulated households and firms be more interesting than a three-valve controller, and could players still read it?
- Can an AI advisor turn valve inputs into a plain causal explanation of why demand is low?