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Modding Guide for Subway Builder

Learn how to create mods for Subway Builder using the JavaScript API

Subway Builder exposes a comprehensive JavaScript API for modding. Mods can add custom cities, map tiles, UI components, game rules, and more.

What Can You Build?#

  • Custom Cities - Add your own cities with custom maps, demand data, and buildings
  • UI Components - Create custom panels, buttons, and overlays
  • Game Modifications - Adjust train types, station behaviors, and game rules
  • Visual Customization - Add custom map layers, themes, and styles
  • Career Missions - Create custom challenges with win conditions

API Version#

Current version: 1.0.0

Check it in the browser console:

javascript
console.log(window.SubwayBuilderAPI.version); // "1.0.0"

No Imports Needed#

Mods run as plain JavaScript via `new Function()`, so ES6 `import` statements won't work. But you don't need them! Everything you need is exposed on window.SubwayBuilderAPI:

javascript
const api = window.SubwayBuilderAPI;

// React & UI - no imports needed!
const { React, icons, components } = api.utils;
const { Button, Card, CardContent, Progress, Switch, Label, Input, Badge } = components;
const { Settings, Play, Pause, Train, MapPin } = icons; // Curated Lucide set (see UI Components guide)
const h = React.createElement; // Shorthand for building UI

// Game data - no imports needed!
const routes = api.gameState.getRoutes();
const budget = api.gameState.getBudget();
const stations = api.gameState.getStations();

// Actions - no imports needed!
api.actions.setMoney(1_000_000_000);
api.actions.setPause(true);

What's Exposed#

  • api.utils.React - Full React library
  • api.utils.icons - Curated Lucide icons (Settings, Play, Train, etc.). See the list in UI Components
  • api.utils.components - shadcn/ui components (Button, Card, Progress, Switch, Label, Input, Badge, Tooltip, Slider)
  • api.utils.charts - Recharts library (LineChart, BarChart, PieChart, etc.)
  • api.utils.i18n - Translation helper for multi-language mods
  • api.gameState.* - All game data (routes, stations, trains, budget, ridership, metrics)
  • api.actions.* - Game actions (setMoney, setPause, setSpeed)
  • api.hooks.* - Lifecycle hooks (onGameInit, onDayChange, onGameEnd, etc.)

Next Steps#