Chess Play Library

The Chess Play Library is a lightweight Kotlin-based library designed to handle chess game logic. It provides a robust set of tools for managing chess boards, piece movements, and standard notations.

Key Features

Board Management: Initialize a chess board with the standard starting position or any custom setup.
FEN Support: Import and export game states using Forsyth-Edwards Notation (FEN).
Move Execution: Perform moves using coordinate-based Move objects or directly via Standard Algebraic Notation (SAN) strings like e4, Nf3, or O-O.
Game Rules: Includes logic for piece reachability, captures, castling, en passant, and pawn promotion.
State Tracking: Automatically updates side to move, castling rights, en passant targets, halfmove clock, and fullmove number.
Move History: Maintains a chronological list of all moves played on the board.

Usage Examples

Initializing a Board

val board = Board.createDefault()
// Or from a FEN string
val customBoard = Board.fromFen("rnbqkbnr/pp1ppppp/8/2p5/4P3/8/PPPP1PPP/RNBQKBNR w KQkq c6 0 2")

Performing Moves

// Using coordinates
val board = Board.createDefault()
    .move(Move(Square(File.E, Rank.R2), Square(File.E, Rank.R4)))

// Using SAN
val updatedBoard = board.move("Nf3")
    .move("e5")
    .move("Bc4")

Exporting State

val currentFen = board.toFen()
// Access played moves
val history = board.playedMoves

Architecture

The library is built with a clean separation of concerns:

Board: The aggregate root representing the current game state and pieces.
SanMapper: Handles the complexity of parsing human-readable notation into executable moves.
ChessEngine: Cohesive engine for chess game logic, combining movement rules and board processing.
FenMapper: Manages the conversion to and from the FEN string format.

Last modified: 28 March 2026