My next update to my Gambiteers Guild site will hopefully result in a near-complete coverage of the King's Gambit, as I am currently examining the Falkbeer Counter-Gambit and the Declined, with 1.e4 e5 2.f4 Bc5. It appears that Boris Alterman in his gambit series has come up with some interesting ideas for Black in the "true" Falkbeer (with 1.e4 e5 2.f4 d5 3.exd5 e4) which, though not bringing Black close to full equality, ensure that the line is worth taking more seriously than I thought.
Indeed, a few months ago I had quite an embarrassing loss as White in that variation where I played 4.d3 Nf6 5.dxe4 Nxe4 6.Nf3, the most critical response, but then lost my way.
But while my site continues to get updated slowly, in the meantime I will discuss some of my own practical encounters.
Remarkably, Lev Gutman's recommendation against the critical Ziegler Defence to the Blackmar-Diemer Gambit (1.d4 d5 2.e4 dxe4 3.Nc3 Nf6 4.f3 exf3 5.Nxf3 c6 6.Bc4 Bf5 7.Bg5 e6 8.Nh4!? Bg6 9.Nxg6 hxg6 10.Qd3) still hasn't been tested according to the Chesslive.de database. But I managed to reach it via transposition in a very recent game of my own. Although I lost the game, I felt that I had decent chances out of the opening.
1. e4 c6 2. d4 d5 3. Nc3 dxe4 4. Bc4 Bf5 5. f3 exf3 6. Nxf3 e6 7. Bg5 Nf6 8.
Nh4 Bg6 9. Nxg6 hxg6 10. Qd3 Be7 11. O-O-O Nbd7 12. h4
12...Nb6 13. Bb3 Nbd5 14. Ne2 b5 15. Rhf1 a5 16. c4 bxc4 17. Bxc4 O-O 18. Nf4 Nxf4 19. Bxf4 Nd5 20. Be5 Bf6
21. g4 Bxh4 22. Rh1 Bg5+ 23. Kb1 Ne3 24. Rdg1 Nxc4 25. Qh3 f6 26. Qh7+ Kf7 27.
Bxf6 Bxf6 28. Rh6 Qxd4 29. Qxg6+ Ke7 30. Rh3 Qxb2# 0-1
The move-order from the Caro-Kann was pretty unusual- normally Black plays 4...Nf6 and then 5.f3 exf3 6.Nxf3 is a straight transposition to the Ziegler Defence. With the move-order 4...Bf5 5.f3 exf3 6.Nxf3 e6, Black can consider meeting 7.Bg5 with 7...Be7!?, which appears to be completely unexplored. My preliminary suggestion is 8.Qd2 intending 9.0-0-0, and if 8...Bxg5 9.Nxg5.
With the retreat 14.Ne2 I began to go astray, but the computer suggests that 14.Kb1 would have given White decent compensation for the pawn, and after 14...b5 (the problem with 14.Ne2 is rather 14...Ng4) 15.Nf4 White would also have been doing fine. The final straw was the wildly over-optimistic 25.Qh3?, when I failed to realise that Black could simply create a secure escape hatch for the king with 25...f6. The idea of Qd3-h3 works for White in some lines following the natural recapture with 25.Qxc4. I also missed a "shot" with 24.Bxe6!.
An interesting fighting game and not particularly discouraging for White's cause, despite the loss. However, I still believe that the most critical line of the Blackmar-Diemer complex is the Gunderam Defence with 1.d4 d5 2.e4 dxe4 3.Nc3 Nf6 4.f3 exf3 5.Nxf3 Bf5, rather than 5...c6 6.Bc4 Bf5.