Chess

The all-time classic written for the command line

play with a friend, against one of the custom built ai engines or watch the different ai algorithms compete.

Installation

• download zip or git clone https://github.com/mmabraham/Chess\n bundle install\n
• difficulty can be customized by editing the MAX_DEPTH constant within any of the ai player files.

Game play

ruby chess.rb\n to begin a game.

• The default settings will begin a game against the computer, with the human playing as white.
• running the game with the flag -h will start a game with 2 human players
• running the game with the flag -c will start a game with 2 computer players, with 'BFSPlayer' as white
• use the arrow keys or w s a d to move the cursor.
• space or enter to select or drop a playing piece.

Features

• Two custom built ai engines of various difficulty
• Both use a min-max algorithm by interpreting into a single score the board layout that would result from every valid move.
• DFSPlayer internally creates a tree depth first, up to the desired depth. It then immediately sets the score for each node.
• BFSPlayer creates the tree breadth first, potentially allowing it to run on a concurrent thread while waiting for the opponent's input and looking up scores only when required to move.

Implementation

• Every player class has the same API allowing the game to interact with all players polymorphically.
• Uses modules to extract methods common to several types of pieces and keep the code DRY. i.e. queen, rook and bishop include the slidable module.

class Rook < Piece
  include Slidable

  def symbol
    :R
  end

  def value
    5 + super
  end

  private

  def move_dirs
    [[0, 1], [0, -1], [1, 0], [-1, 0]]
  end
end