What this blog is for
The in-game advisor and the player guides tell you what to do next. This blog explains why the rules are the way they are. Most entries come straight from design documents and change logs that were written while the feature was being built, so the numbers quoted here are the numbers in the game at the time of publication. When a later update changes a rule, the relevant article is revised and the modification date is updated.
Articles are tagged either Game systems (how a mechanic works and how to use it) or Dev log (what changed, what we measured, and what we decided not to do). If you are new to the game, start with How to Play and come back here when you want the deeper explanation.
Schools, classrooms, and the school bus: how education coverage actually spreads
Seats, not circles: how a high school decides who it teaches, what classrooms and the bus garage change, why the university has no radius, and why factories stall when schools are full.
Game systemsHow city rank works: the six population milestones and what each one unlocks
Town to Megacity: the exact population thresholds, the buildings each rank opens, how City Hall department slots work, and a route through the ladder for a first city.
Game systemsHow land value works in BuildCity: the numbers behind every neighborhood
Service radius, land value bonuses, density thresholds, and why one school can change the shape of a whole district.
Game systemsIdle income explained: the 24-hour cap and what happens while you are away
How offline taxes accumulate, why the second day is worth half, and how to plan check-ins around the cap.
Game systemsFire, crime, and disease: how coverage radius decides what a disaster costs you
What actually happens when a fire starts, how far a fire station reaches, and why coverage beats response time.
Dev logWhy we flattened the tax curve: inside the September 2026 economy update
High-density towers were paying far too much. Here is the exact formula we shipped, the trade-offs, and what it means for your budget.
Dev logDesigning a new map: what it takes to ship White Sands Coast and the Grand Canyon
Logical tile grids, 3D terrain masks, resource placement, and the background-horizon rule we now apply to every map.
Game systemsTourism in BuildCity: attractiveness, visitor income, and the Tourism Bureau
How landmarks, casinos, and road access combine into a visitor economy, and the October rebalance that added per-visitor costs.
Game systemsSister cities: how cooperative play works between two mayors
Matching, bond levels, shared weekly tourist goals, caretaking a partner's city, and the dormancy rules that keep partnerships honest.
Dev logRunning a 3D city on a low-end PC: the white-screen fix and the lightweight recovery mode
What broke on 4 GB machines, how the loading screen now waits for a real first frame, and what the recovery mode turns off.
Dev logHow traffic moves in BuildCity, and why we have not turned on traffic lights yet
Physics ticks versus render frames, the interpolation fix that stopped vehicles teleporting, and the real cost of signals.
Game systemsResource chains: coal, ore, and oil from the mine to the export dock
Where deposits come from, what a smelter and refinery actually do, and how trade buildings turn stockpiles into cash.