♟️ 2D Java Chess

A classic chess game built in Java with a Swing graphical interface.
You play as White against a simple AI opponent (Black), with legal move highlighting, castling, en passant, promotion, and checkmate detection.

This project is a complete rewrite of an earlier Python/Pygame version, with improved UI/UX, bug fixes, and a more maintainable object‑oriented structure.

---

✨ Features

• Graphical board (640×640) with light/dark squares
• All standard chess rules implemented:
  • Castling (kingside & queenside)
  • En passant captures
  • Pawn promotion (auto‑queen)
  • Check and checkmate detection
  • Stalemate draw
• Click‑based piece movement
  • Click a piece to see legal moves (dots)
  • Click a destination to move
• AI opponent (Black)
  • Minimax with alpha‑beta pruning (depth 2)
  • Positional evaluation using piece‑square tables
  • Move ordering for better pruning
• Fixed bugs from the Python version:
  • En passant capture now removes the correct pawn
  • No infinite recursion when checking attacks (castling vs. attack detection separated)
  • Piece images preserve aspect ratio – no distortion
• Improved UI/UX:
  • Selected square highlighting
  • Legal move indicators
  • Game over message
  • (Optionally extendable: coordinates, last move highlight, check highlight, etc.)

---

🛠️ Requirements

• Java 17 or later (uses records – Java 16+ required)
• No external libraries – only standard JDK

---

🚀 How to Run

1. Compile the source files
   Place all .java files in the same directory (or package). Then:

   javac *.java

2. Place the assets
   Create an assets folder in the same directory as your compiled classes (or in the classpath root) and put the piece PNGs inside it.
   The expected filenames are:

   w_King.png, w_Queen.png, w_Rook.png, w_Bishop.png, w_Knight.png, w_Pawn.png
   b_King.png, b_Queen.png, b_Rook.png, b_Bishop.png, b_Knight.png, b_Pawn.png
   

   (You can reuse the original Itch.IO assets.)

3. Run

   java Main

---

🎮 Gameplay

• You control White; the AI controls Black.
• Click a white piece to select it – legal moves are shown as small dots on empty squares.
• Click a destination square to move.
• If you click another white piece, the selection changes.
• Click the selected piece again (or an illegal square) to deselect.
• The AI will automatically make its move after a short delay (500 ms).

Special Moves

• Castling: Move the king two squares toward a rook; the rook jumps automatically.
• En passant: If a pawn moves two squares forward and lands beside an enemy pawn, the enemy pawn may capture it as if it had moved only one square.
• Promotion: When a pawn reaches the last rank, it is automatically promoted to a Queen.

---

📁 Project Structure

src/
├── ChessGame.java      – Core chess rules, move generation, board state
├── ChessAI.java        – Minimax AI with evaluation
├── ChessPanel.java     – Swing panel drawing board and pieces
├── Config.java         – Constants, colors, piece‑square tables
├── ImageLoader.java    – Loads piece images from resources
├── Main.java           – Entry point, sets up the frame and AI timer
└── Move.java           – Simple record representing a chess move
assets/                 – PNG images for all pieces

---

🧠 AI Details

• Algorithm: Minimax with alpha‑beta pruning (depth 2)
• Evaluation:
  • Material values: Pawn=1, Knight=3, Bishop=3, Rook=5, Queen=9
  • Positional bonuses from piece‑square tables
• Move ordering: Captures and promotions are searched first to improve pruning efficiency.

---

🔧 Possible Enhancements

The current implementation is clean and modular. You can easily extend it with:

• Promotion dialog (choose Queen, Rook, Bishop, Knight)
• Board coordinates (a‑h, 1‑8)
• Last move / check highlighting
• Undo / redo
• Adjustable AI difficulty (depth or time‑limited search)
• Sound effects / animations
• Pause / restart buttons

---

📝 License & Credits

• Chess piece assets: Original assets from Itch.IO (free assets).
  If you use this project, please keep the original asset license in mind.
• Code: This project is open for learning and modification.

---

Enjoy the game! 🏆