Blackmar-Diemer Gambit: what should White play?

In the Blackmar-Diemer Gambit (ECO D00), White must decide how to continue development while addressing the advanced Black pawn on e4. The engine-recommended continuation is Bg5, evaluating at -0.61, which pins Black's defensive knight and prepares rapid piece activity. Alternatively, f3 represents the primary gambit idea, offering the pawn to accelerate development and opening lines for the pieces.

Gambit Acceptance and f3

While the engine prefers the bishop development, f3 remains the overwhelming practical choice, occurring in 72.4% of recorded games (5.83M recorded). White scores 54.7% from this position, seeking active central piece play after opening the f-file. An illustrative engine continuation follows the path f3 exf3 Nxf3 c6 Bd3 Bg4, where White regains the material balance or develops smoothly at the cost of a slightly lower engine evaluation (-0.65).

The Engine Recommendation: Bg5

The top engine choice, Bg5, appears in 21.4% of recorded games (1.72M recorded), with White scoring 52.6%. This move immediately challenges Black's control over the center by targeting the f6 piece. An illustrative engine continuation demonstrates how White increases pressure on the opponent's structure: Bg5 Bf5 Bxf6 exf6 Qe2 Nc6. By trading on f6, White doubles Black's pawns and readies queen pressure against the e4 pawn.

Other Developmental Alternatives

White also possesses several minor tries that postpone the direct gambit strike. The move Bc4 features in 4.8% of recorded games (387K recorded, scoring 48.4%, eval -0.85), leading into Bc4 Nc6 Be3 a6 a3 e6. Similarly, Nge2 occurs in 1.4% of games (109K recorded, scoring 46.8%, eval -0.79), with the illustrative continuation Nge2 Bf5 Ng3 e6 Bg5 Bb4. Lastly, h3 is assessed at -0.76, where the engine indicates h3 Nc6 Nge2 Bf5 d5 Nb4.