MarsGo: Marseille Chess Logic Library

Version 1.0.0-alpha | Author: itsVentie

A lightweight, robust Go library for implementing Marseille Chess (double-move variant) rules. Built on top of notnil/chess, MarsGo handles the complex sub-turn logic and check-validation specific to the Marseille variant.

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♟️ What is Marseille Chess?

Marseille Chess is a tactical variant where players move twice per turn.

• Balanced Start: White moves only once on the first turn.
• The Check Constraint: If a player gives Check on their 1st sub-move, their turn ends immediately.
• Tempo: Games are significantly faster and more volatile than standard chess.

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📂 Library Structure

MarsGo/
├── api/                # API definitions (gRPC/Proto and OpenAPI)
├── cmd/
│   ├── cli/            # Interactive Terminal Interface
│   └── server/         # Backend server implementation (Engine API)
├── frontend/           # Web-based UI (Next.js/React)
├── internal/           # High-performance core (Bitboards, Search, Eval)
│   ├── bitboard/       # Bitboard representation of the board
│   ├── search/         # Search algorithms (Minimax/Alpha-Beta)
│   └── evaluation/     # Board scoring heuristics
├── pkg/                # Publicly accessible libraries
│   ├── engine/         # Marseille Protocol & Game State Machine
│   ├── notation/       # FEN & PGN parsing
│   └── uci/            # UCI protocol handler for GUI compatibility
├── tests/              # Integration and Benchmark suites
├── go.mod              # Dependency management
└── README.md           # Project Documentation

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🛠 Installation

go get [github.com/itsVentie/MarsGo](https://github.com/itsVentie/MarsGo)

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🚀 Running the Project

1. CLI Mode (Terminal)

Play directly in your terminal using the built-in CLI tool:

go run cmd/cli/main.go

2. GUI Mode (Fullstack)

To run the web interface, you need to start both the backend server and the frontend development server.

Start the Engine Server:

go run cmd/server/main.go

Start the Frontend:

cd frontend
pnpm install
pnpm dev

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⚙️ Core Logic Implementation

🛡 Deep Scan Validation

MarsGo implements a Geometric Attack Scanner. Since standard FEN manipulation can sometimes "blind" standard engines to checks in non-standard positions, MarsGo manually verifies king safety after every sub-move to ensure compliance with the Marseille "Check-End" rule.

🔄 State Reconstruction

The library uses a History-Based Reconstruction for the Undo() function. This ensures that even in complex double-move sequences, the internal board state remains 100% consistent with the move history.

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🏗 Roadmap (Alpha v1)

• v1.1.0: Minimax AI integration specifically tuned for $40^2$ branch factors.
• v1.2.0: Full PGN support for Marseille-style move notation.
• v2.0.0: Plug-and-play move validation for web-based multiplayers.

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Contributing

Issues and PRs are welcome. Help us make the Marseille variant more accessible to the Go community.

📄 License

MIT License. Created by itsVentie.