Lemonade Bench

Lemonade Bench lets a tool-using language model play Lemonade Tycoon Deluxe as a text-only, long-horizon business benchmark while the original game remains visible under Wine. The agent receives semantic MCP tools for the same information and actions available through the game UI; it never receives vision, arbitrary memory access, shell access, or internet access.

The project contains three pieces:

• a 32-bit Windows proxy DLL loaded by the game, exposing a loopback bridge;

• a Player MCP that turns UI state and actions into semantic tools;

• a provider-agnostic benchmark runner with tracing, crash recovery, compaction, optional model-authored notes, and reports.

The complete reverse-engineering and control path is explained in How it works, from the FMOD proxy DLL to the zero-vision MCP runner.

Compatibility

The bridge and memory map are tested only with Lemonade Tycoon Deluxe 1.1.9, 32-bit Windows executable SHA-256:

5f079edaba4963765ce650efe25f2c12673b8c889539c6dc8a426e34a94dc7e3

Earlier releases, later releases, localized executables, and modified binaries are unsupported. Their memory addresses or UI coordinates may differ. The launcher refuses an unknown executable unless the operator explicitly enables the unsafe override.

This repository does not include the game, an installer, saves, assets, FMOD, or a Wine prefix. You must provide your own legitimate installation.

Related MCP server: LLMMO Game Server

Requirements

• Lemonade Tycoon Deluxe 1.1.9;

• a Wine-compatible environment capable of running the game;

• Node.js 22 or newer;

• Tesseract available on PATH for menu/save bootstrap OCR;

• an i686 Windows Clang/MinGW toolchain to build the bridge;

• an OpenAI or OpenRouter API key for model-driven runs.

Installation

Create a dedicated copy of the installed game directory. Benchmark scenarios remove Lemonade.dat to create a fresh career, so never point the runner at the only copy of personal saves.

npm install
cp .env.example .env.local

Edit .env.local and set at least:

LEMONADE_GAME_DIR=/absolute/path/to/dedicated/game-copy
LEMONADE_WINE_BIN=wine
LEMONADE_WINE_PREFIX=/absolute/path/to/dedicated/wine-prefix
LEMONADE_ALLOW_SAVE_RESET=true

Build the proxy before replacing the game's FMOD loader:

native/build_proxy.sh \
  /absolute/path/to/llvm-mingw \
  "/absolute/path/to/dedicated/game-copy/fmod.dll" \
  dist

Then install it. The setup script verifies the executable and original FMOD hashes, renames the user's original to fmod_original.dll, installs the proxy, and writes the dedicated-install safety marker.

npm run setup -- install-bridge
npm run setup -- doctor

Restore the original FMOD loader at any time with:

npm run setup -- uninstall-bridge

See docs/installation.md for the full bootstrap and failure modes.

Running a benchmark

First validate the local game and Player MCP without spending model tokens:

npm run runner:doctor

Then validate the selected paid model transport with one minimal tool call:

npm run runner:preflight

Run the 30-day validation or the 360-day benchmark:

npm run runner -- run benchmark-career-30d
npm run runner -- run benchmark-career

Resume an interrupted run without resetting the game:

npm run runner -- resume /absolute/path/to/run-directory

The standard scenario deletes saves only inside the marked dedicated game copy, creates a new BENCHMARK career in slot 1, reaches Year 1 / Month 1 / Day 1, and then hands control to the model.

Scoring

The benchmark records two terminal signals:

total economic value = cash + equipment value + inventory replacement value
liquid cash          = cash

Total economic value is primary; cash is the secondary liquidity score. Equipment uses the value displayed by the game's balance sheet. Inventory is valued at the lowest unit replacement cost available in the visible supply catalog, with the final total rounded to the nearest cent. This makes a final upgrade purchase score-neutral at purchase time instead of treating investment as destroyed wealth.

Every run stores the exact scoring method and emits raw traces, a resumable checkpoint, analysis.json, and REPORT.md under the ignored runs/ directory. See docs/benchmark-contract.md.

Player boundary

The DLL contains developer primitives because the driver must capture the window, click controls, type a company name, read mapped values, and stop the game. Those primitives are never registered on the Player MCP. Before starting a paid episode, the runner compares the complete tool surface with an exact allowlist and rejects every unexpected or missing tool.

The semantic MCP deliberately exposes approximate popularity and satisfaction bars instead of hidden percentages, and omits internal demand equations, upgrade magnitudes, and optimal strategies. See docs/player-visibility-audit.md. The complete local trust boundary is documented in docs/security-model.md.

Tests

Pure tests do not require the game:

npm test

Game integration tests require the configured dedicated installation:

npm run test:bridge
npm run test:player-visibility
npm run test:gameplay

Legal and project status

This is an independent interoperability and AI research project. It is not affiliated with or endorsed by the developers, publishers, or rights holders of Lemonade Tycoon Deluxe. No game files or DRM bypass are provided. Users are responsible for complying with the software license and applicable law in their jurisdiction.

The code is provided under the MIT License. The upstream repository does not accept issues or pull requests; fork it if you want to modify or maintain it. See GOVERNANCE.md.

Development provenance

The original concept, product direction, benchmark requirements, and live game validation were led by Maxence Marchal. Reverse engineering, implementation, debugging, tests, and the initial documentation were produced collaboratively through Codex using GPT-5.6 Sol with High reasoning effort.