HIARCS chess engines use new play realism capabilities which give a much more realistic human like feel to the play of the weaker set Elo opponents in the HIARCS chess engine. In particular it tries to produce the same sorts of mistakes and common moves that weaker players are prone to. This enables you to get genuinely useful practice against our handicap opponents as they will challenge you very much like a human player of that strength while making similar mistakes to players of that strength. In addition it matches the opening book moves to the playing strength and even forgets its book moves or mixes up move orders to simulate real play.