🏙️ PolyCity — 3D City Builder

PolyCity is a full-featured, free, open-source city-building simulation that runs entirely in your browser. Zone districts, wire up power, keep citizens happy, fight fires, balance the budget — and grow a tiny island outpost into a glittering megalopolis.

Built with Three.js + Vite, zero runtime dependencies beyond the engine, procedural graphics (no asset downloads), and a simulation modeled on the classics.

✨ Features

🗺️ Procedural islands	Every new map is unique — winding rivers, beaches, forests
🏘️ RCI zoning	Residential / commercial / industrial with demand-driven growth
⚡ Power grid	Coal, solar & wind plants; brownouts when demand exceeds supply; wind turbines get +50 % on the coast
📈 Land value & upgrades	Parks, plazas, services and waterfronts raise land value; buildings grow through 3 density tiers
🚓 City services	Police, fire stations, hospitals and schools shape happiness and value
🔥 Disasters	Pollution-driven fires spread and are contained by fire coverage; mature cities face tornadoes that flatten whole streets (toggle in settings)
💰 Budget & taxes	Live tax slider, itemized income/upkeep ledger, debt warnings
🚗 Traffic	Animated cars flow along your road network
🌗 Day/night cycle	Windows light up as the sun sets
🪄 Auto-Build advisor	One click founds a town, then keeps power ahead of demand, connects zoned land, adds districts and services where coverage lags — always keeping an emergency reserve
🎯 Goals & milestones	From Outpost to Megalopolis, with an onboarding quest list
💾 Saves	Autosave, 3 manual slots, JSON export/import
📱 Touch support	Paint with one finger, pinch-zoom, two-finger rotate
🔌 PWA	Installable, offline-capable via service worker

🎮 Controls

Action	Input
Use tool / paint	Left-drag or one finger
Orbit camera	Right-drag or two fingers
Pan	Middle-drag, or WASD / arrow keys (Shift = faster)
Zoom	Mouse wheel / pinch
Pause · speed	Space · 1 2 3
Tools	Q inspect · B bulldoze · R road · Z/X/C zones
Close / cancel	Esc · Help: H

How to play in 30 seconds

1. Drag an L-shaped road from the coast inland.
2. Paint homes beside it, then some shops and industry.
3. Drop a coal plant anywhere — power is a city-wide grid.
4. Press ▶▶ and watch the neighborhood fill in.
5. Add police/fire/parks to push land value past the upgrade thresholds.

🚀 Run it locally

pnpm install
pnpm dev        # dev server → http://localhost:5173

📦 Production build

pnpm build      # outputs static site to dist/
pnpm preview    # serve dist/ locally

The build is fully static and relative-path based — drop dist/ on any host.

🌍 Publish it

GitHub Pages — this repo ships .github/workflows/deploy.yml; push to main and enable Pages (Settings → Pages → Source: GitHub Actions).

Netlify / Vercel / Cloudflare Pages — import the repo, build command pnpm build, publish directory dist. A ready-made netlify.toml is included.

itch.io — zip the contents of dist/ (keep index.html at the zip root), upload as an HTML5 game, check sharedarraybuffer is not needed and any resolution; the game auto-fits.

🧪 Tests

node tests/engine.mjs   # 40-assertion simulation suite (pure Node)
node tests/soak.mjs     # 40-year economy/growth/power soak test
node tests/smoke.mjs    # headless-browser end-to-end run
node tests/capture.mjs  # renders promo screenshots into shots/

🛠️ Tech notes

• One shared MeshStandardMaterial + instanced meshes draw the entire city in a handful of draw calls; geometry is merged & vertex-colored at load time.
• Simulation runs on typed arrays (64×64 tiles) with monthly ticks decoupled from rendering; speeds pause / 1× / 2× / 3×.
• Adaptive resolution keeps frame times sane on weak GPUs.
• All audio is synthesized WebAudio — no assets, no tracking, no network calls.

License

MIT — build, remix, ship it. 🏗️