RubyKnight is a very naive implementation of a chess library and engine.
gem install rubyknight
> rubyknight
require 'rubygems'
require 'rubyknight'
board = RubyKnight::Board.new
puts board.to_s
print "Enter move: "
$stdin.each do |move|
move.strip!
begin
board.cnotation_move move
rescue RubyKnight::IllegalMoveException
print "Enter a real move! #{$!.to_s}\n"
end
puts board.to_s
print "Enter move: "
end