Chess Opening Theory/1. d4/1...Nf6/2. g4

2. g4!? is an uncommon gambit line against the Indian defence. White offers the g pawn to deflect Black's knight from controlling the centre.

If Black accepts, 2...Nxg4, White can play 3. e4, achieving a two-pawn centre and scoring tempo on the knight (discovered attack from White's queen). If Black retreats, 3...Nf6, White can continue to expand their centre while scoring tempo on the knight 4. e5 Nd5 5. c4 Nb6 =. Alternatively, Black can try try 3...d6 or 3...d5 (bishop defends knight). After 4. Be2 Black must retreat their knight anyway. In exchange for the pawn, White can often get a two pawn centre and a development lead.

Declining the gambit with 2...d5 allows 3. g5 to kick the knight. If White wants, they can eventually get their two pawn centre after 3...Ne4 4. f3 (c4 is engine continuation) Nd6 5. Nc3 Nc6 6. e4 dxe4 7. fxe4.

Alternatively, 2...h6 declines the gambit and prevents 3. g5. This allows Black to play d5 without getting kicked by 3. g5, e.g. 3. Nf3 d5 (to control e4, renewing threat of Nxg4) 4. h3 (defending g4).

2. g4!? is known as the Bronstein gambit or the Gibbins-Weidenhagen gambit. It is very rare in tournament games. The engine considers White's development lead to not quite compensate for the pawn and weakened kingside but its evaluation only gives Black a slight edge and it scores well enough for White in club level games^[1], so may be worthy of further exploration.

For explanation of theory tables, see theory table and for notation, see algebraic notation.

1. d4 Nf6 2. g4

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