From Wim van Beusekom:
MacChess is a simple adaptation of this classic strategy game. Features include easy levels for beginners to play, an expanded opening book, an option to show you your best move, and a log to record your moves. In addition, MacChess can play against GNUChess, Crafty, or other chess applications when using the ExaChess Lite utility. MacChess is no cream puff of a game--it has some levels that are mighty hard to whip, and it has won awards in some hardcore computer chess tournaments. It now includes a move generator, a larger chess board and classic piece set, a results window, and new icons.