Amar Opening

The Amar Opening, 1. Nh3, is an irregular first move classified under A00. It also goes by the Paris Opening and the Drunken Knight Opening, and is sometimes called the Ammonia Opening because the notation resembles the chemical formula NH3. Its name comes from Charles Amar, a Parisian amateur who played it in the 1930s. Savielly Tartakower probably coined the name, and Tim Harding has joked that "Amar" stands for "Absolutely mad and ridiculous".

The move is not a blunder, but it does little for White. On h3 the knight exerts no influence over the central squares, and White effectively hands the first move to Black. Black can adopt almost any sound opening setup with an extra tempo in hand. The engine gives Black a slight edge, and Black scores better than White in practice.

The most common reply is 1...d5, which opens the c8-bishop and threatens 2...Bxh3, doubling White's kingside pawns. White normally answers 2. g3, covering the knight with a future Bg2 fianchetto, after which 2...e5 lets Black build a broad pawn center. The alternative 1...e5 is nearly as popular and gives Black even better results, while 1...e6 is a quieter option.

The best-known named line is the Paris Gambit, 1. Nh3 d5 2. g3 e5 3. f4, in which White strikes at the center at the cost of material. After 3...Bxh3 4. Bxh3 exf4, Black has won a pawn and keeps a solid hold on the center, so the gambit is regarded as dubious. Its one named sub-line is the Gent Gambit, 5. O-O fxg3 6. hxg3, in which White gives up a second pawn for open lines against the black king. Tartakower first played it against Andor Lilienthal in Paris in 1933.

At a serious level the opening is mainly a surprise weapon or a provocation. Magnus Carlsen used it to beat Aleksey Dreev in a rapid game in the 2018 online PRO Chess League.