The Rousseau Gambit is a dubious chess opening characterised by the moves (in algebraic chess notation):

1.Chess/Opening Theory/1.e4 Chess/Opening Theory/1.e4/1...e5

2.Chess/Opening Theory/1.e4/1...e5/2.Nf3 Chess/Opening Theory/1.e4/1...e5/2.Nf3/2...Nc6

3.Chess/Opening Theory/1.e4/1...e5/2.Nf3/2...Nc6/3.Bc4 Chess/Opening Theory/1.e4/1...e5/2.Nf3/2...Nc6/3.Bc4/3...f5

The gambit is named after Eugéne Rousseau. White's best response is to simply decline the gambit and continue by supporting the e pawn and developing with 4.Chess/Opening Theory/1.e4/1...e5/2.Nf3/2...Nc6/3.Bc4/3...f5/4.d3. The resulting position is similar to a King's Gambit Declined with Black playing the gambit with less development, and White's king bishop pointing at Black's weakened king-side -- not very comfortable for Black. Black will have trouble castling kingside and Ng5 is a likely threat. White's position is better, but still requires careful play.

Key themes for White are to attack Black's kingside and to avoid attempts by Black to simplify the position via exchanges. Exchanges involving White's light bishop are particularly suspect.

The best advice for Black is to not play this gambit as it is considered refuted.

Rousseau Gambit Declined

White's best response is to decline the gambit and to wait to capture the f pawn.

1.Chess/Opening Theory/1.e4 Chess/Opening Theory/1.e4/1...e5

2.Chess/Opening Theory/1.e4/1...e5/2.Nf3 Chess/Opening Theory/1.e4/1...e5/2.Nf3/2...Nc6

3.Chess/Opening Theory/1.e4/1...e5/2.Nf3/2...Nc6/3.Bc4 Chess/Opening Theory/1.e4/1...e5/2.Nf3/2...Nc6/3.Bc4/3...f5

4.Chess/Opening Theory/1.e4/1...e5/2.Nf3/2...Nc6/3.Bc4/3...f5/4.d3

Rousseau Gambit Accepted

White still has a good game after the inferior 4.exf5, but the position is less clear. Black usually plays 4...e4, which White may meet by 5.Nd4! Nf6 (5...Nxd4? leads to trouble after 6.Qh5+) 6.Nxc6.

1.Chess/Opening Theory/1.e4 Chess/Opening Theory/1.e4/1...e5

2.Chess/Opening Theory/1.e4/1...e5/2.Nf3 Chess/Opening Theory/1.e4/1...e5/2.Nf3/2...Nc6

3.Chess/Opening Theory/1.e4/1...e5/2.Nf3/2...Nc6/3.Bc4 Chess/Opening Theory/1.e4/1...e5/2.Nf3/2...Nc6/3.Bc4/3...f5

4.Chess/Opening Theory/1.e4/1...e5/2.Nf3/2...Nc6/3.Bc4/3...f5/4.exf5

Chess openings

Gambetto Rousseau