Halasz Gambit

The Halasz Gambit is a rare branch of the 2. d4 line against the Sicilian Defense. After 1. e4 c5 2. d4 cxd4, White does not recapture with the queen, offer a second pawn with 3. c3 as in the Smith-Morra Gambit, or prepare Nxd4 with 3. Nf3. Instead 3. f4 gives up the pawn for a broad e4-f4 pawn front and the possibility of a quick kingside initiative. The cost is that Black's pawn stays on d4, where it covers c3 and e3 and gets in the way of White's natural queenside development, while the f-pawn advance also loosens White's king.

Black usually replies 3...Nc6, which accounts for the clear majority of games, develops a piece and adds support to the d4-pawn. Less common alternatives are 3...e6 and 3...d6, and the engine also rates 3...e5 among the best moves, striking at the f4-pawn directly. The engine assessment slightly favors Black, so the gambit is not considered fully sound. In online play, however, the results are almost exactly even, and the opening is mainly used as a practical surprise rather than a theoretically established line.