LPC - Let's Play Checkers!!

A classic Checkers (Draughts) game written in modern C++20, featuring both local two-player mode and various AI opponents, rendered with SFML.
The following checkers variants are supported:

• International
• Russian
• Canadian
• Brazilian

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Features

• Board Logic

  • Board with automatic move generation and capture rules.
  • Piece promotion (regular to queen) at the opposite side.
  • Chained captures supported (multiple jumps in one turn).

• AI Engines

  • Random Engine: Picks a random valid move.
  • Minimax Engine: Employs the Minimax algorithm (with Alpha-Beta pruning) with variable difficulty levels (EASY, MEDIUM, HARD, GRANDMASTER).

• GUI

  • SFML-based user interface with clickable squares.
  • Menu system to select either two-player or computer-vs-human mode, as well as difficulty/AI level.
  • Visual highlights for valid moves, chain captures, and game result screens.

• State Machine

  • Easily extendable system to manage game states (Menu, Play, etc.).

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Some screenshots

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Architecture Overview

This project is split into three main parts:

1. Checkers-logic

   • Checkers class: Handles all move logic, captures, piece promotion, and maintains the turn order. Stores Board
   • Board class: Maintains 8×8 (Russian and Brazilian), 10×10 (International) and 12×12 (Canadian) grid using space-efficient std::array.
   • Exposes functions for retrieving valid moves, making moves, and resetting the board.
   • Tracks game result and winner determination.

2. Engine

   • Engine is an abstract base class providing a getBestMove() method.
   • RandomEngine: Returns a random valid move.
   • MinimaxEngine: Implements a Minimax search. Different difficulty levels limit the search depth. Implemented Alpha-Beta pruning. Added a random component when choosing the optimal move to minimize the probability of getting exactly the same games.
   • Uses an evaluation function in EvaluationFunction.cpp to score board states.

3. GUI

   • SFML-driven interface in the gui directory.
   • StateManager: Maintains a stack of states.
   • MenuState: Lets user select mode (two-player or vs. AI), color for player, and AI difficulty.
   • PlayState: Renders the board, pieces, handles user input, and orchestrates moves from the chosen Engine.
   • ResourceManager: Loads and provides textures and fonts.
   • Button: Simple clickable UI element.

Notable Design Patterns

• Strategy Pattern

  • Engine as the strategy interface; RandomEngine and MinimaxEngine as concrete implementations.

• State Pattern

  • StateManager switches between different GUI states (MenuState, PlayState).

• Factory/Builder-Like

  • Creation of specific engines (ENGINE_MODE → RandomEngine or MinimaxEngine) depending on user choice.

• Observer-Like

  • While not a strict observer pattern, the GUI “observes” changes in the Board state by calling Board::getResult() and re-rendering accordingly.

Core Algorithms

• Move Generation

  • Generates valid moves using Board::generateValidMoves().
  • Forces capture moves if any are available (as in checkers rules).
  • Supports piece promotion and chain captures.

• Minimax with Depth (with Alpha-Beta pruning)

  • Evaluates board states up to a maximum depth (EASY = 2, MEDIUM = 4, etc.)
  • Scores positions using evaluatePosition() for piece advantage and positional bonuses.

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Getting Started

1. Clone the Repository
2. Build (Developed on Debian 12)
   Make sure you have a C++20 compiler and CMake ≥ 3.25.1 installed, plus SFML (version ≥ 2.5).

mkdir -p build && cd build && cmake -DCMAKE_BUILD_TYPE=Release .. && make

3. Run

./LPC

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Usage

1. Launch the game — a window will open with the main menu.
2. Select Checkers type (International, Russian, Canadian, Brazilian).
3. Select Game Mode — either play against the computer (With Computer) or another human locally (Two Players).
4. (Computer mode only) Choose Your Colour — play as White or Black.
5. (Computer mode only) Select Difficulty — choose from Novice, Easy, Medium, Hard, or Grandmaster.
6. Enjoy playing — click the squares to select a piece and move it. Possible moves are highlighted automatically.
7. Press ESC anytime to return to the main menu.

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TODO

1. Implement Undo / Redo

   • Track and revert moves for convenience.

2. Improve AI

   • Implement a transposition table or caching.
   • Add multhithreading (Grandmaster mode can be faster).

3. Online Multiplayer

   • Introduce network play for remote two-player matches.

4. UI Enhancements

   • Turn the board around if playing for black against the computer. Done! 🎊
   • Animate piece captures more smoothly.
   • Add sounds and a game timer.

5. Automated Testing

   • Add unit tests for critical Board methods and engine functionality.

6. Add Documentation