rct2-agent

An MCP server + OpenRCT2 plugin that lets an agent sidecar-manage your park while you play: read the state, act on the business (prices, staff, marketing, loans), see the park (screenshots), and control time. Management only — the agent tunes the business and can recommend building, but never builds.

How it fits together

Claude Code (WSL)
      │ stdio (MCP)
      ▼
MCP server  ── dist/server.mjs, run by Windows node.exe
      │ TCP 127.0.0.1:7860  (newline-delimited JSON)
      ▼
Plugin (intransient) ── loaded inside OpenRCT2, LISTENS on the port
      │
      ▼
   OpenRCT2 game

The server runs under Windows node.exe (there is no node in WSL), so both the server and the plugin sit on the same Windows localhost — no WSL↔Windows networking involved. The plugin listens (it's intransient, so it stays alive across park loads); the server dials in and reconnects as needed.

Requirements

• OpenRCT2 0.5.4+ (QuickJS engine — needed for Promises/ES2023).
• Windows Node.js (found here at C:\Program Files\nodejs\node.exe).

Build & install

From WSL, using the Windows toolchain:

# helper wrappers (or just call node.exe / npm-cli.js directly)
NODE="/mnt/c/Program Files/nodejs/node.exe"
NPM=("$NODE" "C:\\Program Files\\nodejs\\node_modules\\npm\\bin\\npm-cli.js")

"${NPM[@]}" install
"${NPM[@]}" run build          # builds dist/rct2-agent.plugin.js + dist/server.mjs
"${NPM[@]}" run install:plugin # copies the plugin into your OpenRCT2 plugin folder

install:plugin copies to C:\Users\casey\OneDrive\Documents\OpenRCT2\plugin\rct2-agent.plugin.js (override with RCT2_PLUGIN_DIR).

Wire up the MCP server

A ready-to-use project config is in .mcp.json. In Claude Code, from the project directory, it will be picked up automatically (approve it when prompted), or add it explicitly:

claude mcp add rct2-agent --scope project \
  -- "/mnt/c/Program Files/nodejs/node.exe" \
     "C:\\Users\\casey\\OneDrive\\Desktop\\dead code projects\\rct2-agent\\dist\\server.mjs"

Run

1. Launch OpenRCT2 and load a scenario. Confirm the plugin loaded — the in-game console shows [rct2-agent] listening on 127.0.0.1:7860.
2. Start Claude Code in this folder. The MCP server connects on first tool call.
3. Ask the agent to manage the park. The core loop is measure → act → wait → measure: read baselines, make changes, advance_days(7), re-measure.

Tools

Read (eyes): get_park_summary, get_finance_report, list_rides, get_ride, list_shops, get_guest_overview, sample_guest_thoughts, list_staff, get_scenario

Act (hands): set_ride_price, set_shop_price, set_park_entry_fee, open_ride, close_ride, set_inspection_interval, start_marketing_campaign, set_research_funding, hire_staff, fire_staff, set_staff_patrol, set_loan

See (vision): capture_view, capture_ride, find_location

Time: get_clock, set_game_speed, pause, resume, advance_days

Save: snapshot, list_snapshots

Notes on behavior

• Money is in plain dollars at the tool boundary; internally OpenRCT2 stores tenths, converted in src/shared/protocol.ts (MONEY_FACTOR). If a value looks off by 10×, that's the one knob to check.
• Coordinates in capture_view / set_staff_patrol / find_location are in tiles (converted to map units internally).
• advance_days unpauses, runs at max speed, and auto-pauses when the target date is reached — then returns the new clock. It blocks until done.
• Snapshots save to save/agent__<play>__<label>.park, flat in the save root so they appear in the in-game Load Game menu — context.saveGame silently refuses any filename with a path separator, so subfolders are not possible. Restoring is a manual Load in-game — the plugin API can save but not load a park.
• Writes go through game actions, so the game's own limits apply (e.g. the ride price cap). A rejected action comes back as a tool error.

Dev

• npm run typecheck — tsc, no emit.
• node scripts/smoke.mjs — loads the built plugin into a stubbed game and exercises the handlers over a real socket.
• node scripts/mcp-smoke.mjs — spawns the built MCP server and drives it with real MCP JSON-RPC against a fake plugin.

Layout

src/shared/protocol.ts   wire protocol + money conversion + method names
src/plugin/main.ts       the intransient in-game plugin (TCP listener + handlers)
src/server/rct-client.ts reconnecting TCP client to the plugin
src/server/index.ts      MCP server: tool definitions -> plugin methods
esbuild.mjs              builds both bundles
scripts/                 install + smoke tests