A minimax-based chess engine with alpha-beta pruning written in Python.

• Minimax Algorithm: Recursively evaluates chess positions by considering all possible moves
• Alpha-Beta Pruning: Optimizes search by eliminating branches that won't affect the final decision
• Position Evaluation: Scores positions based on material count and piece activity
• Interactive Game Mode: Play against the engine in the terminal
• Configurable Difficulty: Adjust search depth for speed vs strength tradeoff

pip install -r requirements.txt

Or manually install the dependency:

pip install python-chess

import chess
from Basic_Chess_engine import ChessEngine

# Create engine with depth 3 (faster) or 4 (stronger)
engine = ChessEngine(max_depth=4)
board = chess.Board()
best_move = engine.get_best_move(board)
print(f"Best move: {best_move}")

from Basic_Chess_engine import InteractiveChess

# Play against the engine
game = InteractiveChess(engine_depth=4)
game.play_game()

Note: Run interactive mode in terminal, not IDLE.

1. You play as Black, the engine plays as White
2. Enter moves in algebraic notation (e.g., e2e4, e7e5)
3. Type quit to exit

Example game session:

Welcome to Chess Engine!
You are playing as Black. Engine plays as White.
Enter moves in algebraic notation (e.g., e2e4, e7e5)
Type 'quit' to exit.

Engine is thinking...
Engine plays: e2e4

Your move: e7e5

The engine evaluates positions recursively:

• Maximizing Player (White): Tries to find the highest-scoring move
• Minimizing Player (Black): Tries to find the lowest-scoring move
• Pruning: Cuts off branches that can't affect the final decision

Positions are scored based on:

• Checkmate: ±∞ (perfect win/loss)
• Material Count: Piece values (Pawn=1, Knight=3, Bishop=3, Rook=5, Queen=9)
• Piece Activity: Bonus for having more legal moves available
• Stalemate/Insufficient Material: 0 (draw)

• Nodes evaluated and best value are printed after each move
• Adjust max_depth for speed vs strength tradeoff:
  • max_depth=2: Fast but weak
  • max_depth=3: Reasonable balance
  • max_depth=4: Stronger but slower
  • max_depth=5+: Very slow

==================================================
DEMO: Engine vs Engine (first 5 moves)
==================================================

Move 1: White
Nodes evaluated: 400, Best value: 0.0
Best move: e2e4

Move 2: Black
Nodes evaluated: 2150, Best value: 0.0
Best move: e7e5

...

r n b q k b n r
p p p p . p p p
. . . . . . . .
. . . . p . . .
. . . . P . . .
. . . . . . . .
P P P P . P P P
R N B Q K B N R

Py_Chess_Engine/
├── Basic_Chess_engine.py    # Main engine implementation
├── README.md                # This file
├── requirements.txt         # Python dependencies
├── .gitignore              # Git ignore rules
├── LICENSE                 # CC0 License
└── test_chess_engine.py    # Unit tests

pytest test_chess_engine.py -v

• Move ordering optimization (evaluate captures/checks first)
• Opening book support
• Endgame tablebases
• Piece-square tables for better position evaluation
• Time-based search instead of depth-based
• GUI interface (pygame or tkinter)
• UCI protocol support for compatibility with chess GUIs

Creative Commons Zero v1.0 Universal (CC0)

This work is dedicated to the public domain. You can copy, modify, and distribute this software without any restrictions.

• Built with python-chess library
• Minimax algorithm with alpha-beta pruning implementation

• Still a work in progress with planned enhancements
• For best experience, use depth 3-4 for interactive games
• Performance depends on board complexity and search depth