dillonsteyl / chess

C# .NET 6 Chess Library - Modified to allow overrides directly

Gera Chess Library

Chess logic made with C# and ♥ by Geras1mleo

Browse in NuGet

Chess lib includes:

• ChessBoard with 2-dimentional array of Pieces
• Generation, Validation and Execution of Moves on chess board
• Parse:
  • Move object into SAN and back into Move object
• Load and play further:
  • Chess Board from FEN and back to FEN-string
  • Chess Game from PGN and back to PGN-string
• Event handlers are raised:
  • OnInvalidMoveKingChecked - when trying to execute move that places own king in check
  • On(White/Black)KingCheckedChanged - with state (checked or not) and its position
  • OnPromotePawn - with PromotionEventArgs.PromotionResult (default: PromotionToQueen)
  • OnEndGame - with according end game info (Won Side/Draw)
  • OnCaptured - with captured piece and all recently captured pieces (White/Black)
• End Game Declaration: Draw or Resign of one of sides
• Navigation between executed moves:
  • First/Last
  • Next/Previous
  • Also: board.MoveIndex property to navigate directly to specific move
• Cancelation of last executed move

Usage!

Example simple console chess game:

using Chess;

var board = new ChessBoard();

while (!board.IsEndGame)
{
    Console.WriteLine(board.ToAscii());
    board.Move(Console.ReadLine());
}

Console.WriteLine(board.ToAscii());
Console.WriteLine(board.ToPgn());

// Outcome after last move:
// Qh5
//   ┌────────────────────────┐
// 8 │ r  n  b  q  k  b  n  r │
// 7 │ p  p  p  p  p  .  .  p │
// 6 │ .  .  .  .  .  .  .  . │
// 5 │ .  .  .  .  .  p  p  Q │
// 4 │ .  .  .  .  P  P  .  . │
// 3 │ .  .  .  .  .  .  .  . │
// 2 │ P  P  P  P  .  .  P  P │
// 1 │ R  N  B  .  K  B  N  R │
//   └────────────────────────┘
//     a  b  c  d  e  f  g  h  
//
// 1. e4 f5 2. f4 g5 3. Qh5# 1-0

Example random chess game:

using Chess;

var board = new ChessBoard() { AutoEndgameRules = AutoEndgameRules.All };

while (!board.IsEndGame)
{
    var moves = board.Moves();
    board.Move(moves[Random.Shared.Next(moves.Length)]);
}

Console.WriteLine(board.ToAscii());
Console.WriteLine(board.ToPgn());

Track Pieces

Track pieces on position using indexers:

board["c2"]...			// => White Pawn
board['g',8]...			// => Black Bishop

// Counting from 0
board[0, 0]...			// => White Rook
board[new Position(4, 7)]... 	// => Black King

Track captured pieces:

board.CapturedWhite... // => White pieces that has been captured by black player
board.CapturedBlack... // => Black pieces that has been captured by white player
// Properties above work just fine when board has been loaded from FEN

Track kings and their state (Checked/Unchecked):

board.WhiteKing... // => White king position on chess board (Calculated property)
board.BlackKing... // => Black king position on chess board (Calculated property)

board.WhiteKingChecked... // => State of White king (Referred property)
board.BlackKingChecked... // => State of Black king (Referred property)

Move Pieces

Move pieces using SAN/LAN:

board.Move("e4");	// => Good
board.Move("N-f6");	// => Good
board.Move("NXf6");	// => Good
board.Move("dxc3 e.p.");// => Good
board.Move("Pe4");	// => Good 
board.Move("Pe5xd6");	// => Good
board.Move("O-O-O+");	// => Good

board.Move("ne5");	// => Bad
board.Move("e8=K");	// => Bad
board.Move("0-0");	// => Bad

Move pieces using Move object and corresponding positions:

board.Move(new Move("b1", "c3"));

Ambiguity:

if(ChessBoard.TryLoadFromPgn("1. e4 e5 2. Ne2 f6", out var board))
{
  board.ToAscii();
  //   ┌────────────────────────┐
  // 8 │ r  n  b  q  k  b  n  r │
  // 7 │ p  p  p  p  .  .  p  p │
  // 6 │ .  .  .  .  .  p  .  . │
  // 5 │ .  .  .  .  p  .  .  . │
  // 4 │ .  .  .  .  P  .  .  . │
  // 3 │ .  .  .  .  .  .  .  . │
  // 2 │ P  P  P  P  N  P  P  P │
  // 1 │ R  N  B  Q  K  B  .  R │
  //   └────────────────────────┘
  //     a  b  c  d  e  f  g  h  

  board.Move("Nc3"); 	// => Throws exception: ChessSanTooAmbiguousException. Both knights can move to c3
  board.Move("Nc4"); 	// => Throws exception: ChessSanNotFoundException. None of knights can move to c3
}

Load Chess game/board

Load chess board Variant: From Position (using FEN):

board = ChessBoard.LoadFromFen("1nbqkb1r/pppp1ppp/2N5/4p3/3P4/8/PPP1PPPP/RN2KB1R w KQk - 0 1");
board.ToAscii();
//   ┌────────────────────────┐
// 8 │ .  n  b  q  k  b  .  r │
// 7 │ p  p  p  p  .  p  p  p │
// 6 │ .  .  N  .  .  .  .  . │
// 5 │ .  .  .  .  p  .  .  . │
// 4 │ .  .  .  P  .  .  .  . │
// 3 │ .  .  .  .  .  .  .  . │
// 2 │ P  P  P  .  P  P  P  P │
// 1 │ R  N  .  .  K  B  .  R │
//   └────────────────────────┘
//     a  b  c  d  e  f  g  h  

board.CapturedWhite... // => { White Bishop, White Queen }
board.CapturedBlack... // => { Black Rook, Black Knight }

// Stalemate
board.LoadFen("rnb1kbnr/pppppppp/8/8/8/8/5q2/7K w kq - 0 1");
board.EndGame... // => { EndgameType = Stalemate, WonSide = null }

Load full chess game from PGN:

board = ChessBoard.LoadFromPgn(
@"[Variant ""From Position""]
[FEN ""rnbqkbnr/ppp1pppp/8/3p4/4P3/8/PPPP1PPP/RNBQKBNR w KQkq - 0 1""]
            
1.exd5 e6 2.dxe6 fxe6 3.d4(3.f4 g5 4.fxg5) 3... c5 4.b4");

board.ToAscii();
//   ┌────────────────────────┐
// 8 │ r  n  b  q  k  b  n  r │
// 7 │ p  p  .  .  .  .  p  p │
// 6 │ .  .  .  .  p  .  .  . │
// 5 │ .  .  p  .  .  .  .  . │
// 4 │ .  P  .  P  .  .  .  . │
// 3 │ .  .  .  .  .  .  .  . │
// 2 │ P  .  P  .  .  P  P  P │
// 1 │ R  N  B  Q  K  B  N  R │
//   └────────────────────────┘
//     a  b  c  d  e  f  g  h  

Alternative moves and comments are (temporarily) skipped
In further versions:
Navigate between alternative branches, also load branches from PGN
Adding comments to each move

End Game

Declare Draw/Resign:

board.Draw();
board.EndGame... // => { EndgameType = DrawDeclared, WonSide = null }

board.Clear();

board.Resign(PieceColor.Black);
board.EndGame... // => { EndgameType = Resigned, WonSide = White }

Unit Tests

Here you can see all the tests that have been used to test and improve chess library

Benchmarks

Here you can see the evolution of performance of chess library

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Found a bug?

Drop to Issues
Or: [email protected]

Thanks in advance!