Crab Variation

The Crab Variation, 1. a4 e5 2. h4, follows the slow rook-pawn move with its mirror image on the other wing. The name comes from the shape the two advanced rook pawns make, like a crab's raised claws. The move is picked more for that appearance than for any strategic purpose. Its one concrete point is that the h-pawn occupies h4 and so rules out ...Qh4 along the diagonal opened by 1...e5. Otherwise it does nothing for White's development or center and loosens the kingside, so White is effectively two tempi behind. Engines rate the position as clearly better for Black, and Black wins the majority of games in practice.

Black has no need for any special antidote and simply takes the center and develops. 2...d5 is by far the most frequent reply and builds a broad pawn center. 2...Nc6 and 2...Bc5 are the next most common, and the bishop move gives Black the best practical results of the three. Engines prefer 2...Nc6, 2...d5 and 2...Nf6, all straightforward developing or central moves.