A great introduction to the Diemer–Duhm Gambit is now available: 10-page article by Bob Jensen. It concentrates on two critical variations:
Especially 6.fxe4 is an interesting improvement idea to the Kmoch variation:
Jyrki Heikkinen (2091) – Jussi Hämäläinen (2156), 10 + 10 minutes, Helsinki, Finland, January 2010
1.d4 Nf6 2.g4
When the opponent is expecting the Blackmar–Diemer Gambit, it's sometimes good to give him something else to think about. The Gibbins–Weidenhagen Gambit is a good surprise weapon.
2...Nxg4 3.e4 Nf6 4.e5
4...Ng8
4...Nd5 is naturally better.
5.Nc3 d6 6.Nf3 dxe5 7.Nxe5 Nf6 8.Bc4 e6 9.Rg1 c5 10.Be3
Rybka likes 10.dxc5, but having a lead in development, I want to make that lead even bigger, so I continue developing the rest of my pieces.
10...a6
11.Qf3 Qb6 12.O-O-O
This is what I call development: White has developed five pieces in the last five moves. As a result, White has developed all his seven pieces whereas Black has developed only two. As a compensation for that, Black has only one pawn! White has clear advantage (+1.3), says Rybka.
12...cxd4 13.Bxd4
13.Ne4! would have been crushing.
13...Qc7 14.Bb3 Bd7?
14...Bd6 15.Nc4 is better, but White is still winning. After the text, Rybka's assessment is about +5.0.
15.Ne4 Nxe4 16.Qxf7+ Kd8
17.Bb6 Qxb6 18.Rxd7+ Kc8 19.Qe8+ 1-0
Jyrki Heikkinen – Marko Parkkinen, 5 + 5 minutes, Helsinki, Finland, August 2009
1.d4 d5 2.e4 dxe4 3.Nc3 e5 4.Qh5
"What's this?" my opponent asked about this provoking queen move. We have played some BDG games earlier, but few players are interested in analyzing these variations.
4...Qxd4 5.Be3 Qd6 6.Rd1 Qe6 7.Nxe4 Nf6 8.Nxf6+
8...Qxf6?? 9.Nf3?
We didn't see that 9.Bg5 wins the queen because of the threat 10.Rd8#.
9...Nc6 10.Bb5 Bd6
11.Ng5!?
I have plenty of justifications for playing strange moves like this. First, I want to confuse the opponent. The knight doesn't seem to do anything on g5, but it does: it annoys the opponent. Second, I want to provoke the opponent to create weaknesses. Black can drive the knight away with h6, but that could become a target of attack, especially if Black castled kingside.
As a bonus, the move sets a simple trap: 11...O-O?? 12.Qxh7#. Finally, thanks to the unfamiliar opening, my opponent had much less time than me, so I wanted to complicate the position, and make his game even more difficult.
11...h6?
11...Bf5 -/+.
12.Ne4 Qe7 13.O-O O-O
14.Bxh6!
This was quite an instant sacrifice, based on my gut feeling rather than real calculation. I think I have won about 80 % of the games in which I have sacrificed a bishop on h6, so usually I don't have to calculate.
To my surprise, the sacrifice was perfectly correct this time: Rybka recommends it, too.
14...gxh6?
This loses. Rybka suggests a very sharp variation that starts with 14...Nd4 15.Bd3 gxh6 16.Qxh6 f5 17.Bc4+ +/=.
15.Qxh6
15...f5
15...f6 16.Bc4+ Be6 17.Bxe6+ Qxe6 18.Qg6+ Kh8 19.Rd3 Rf7 20.Nxf6! (20.Rh3+?? Qxh3! -+) +-.
16.Bc4+ Rf7 17.Nf6+ 1-0
It's quite fitting that the knight that provoked h6 decides the game.
Afterwards it would be tempting to claim that the game followed a logical plan: after provoking a weakness by 11.Ng5, I simply exploited it by 14.Bxh6. Who knows, maybe I had a subconscious plan because many BDG games of mine have followed this same pattern.
Jyrki Heikkinen — Tuomas Pitkänen, Helsinki, Finland, August 2008
1.d4 f5 2.Nc3
Sometimes I delay e4, and give the opponent a chance to choose some obscure Staunton Gambit variation.
2...g6 3.e4 d6 4.Bd3 fxe4 5.Nxe4
This is not gambit anymore, but the position could have been reached via the Staunton Gambit, say, 2.e4 fxe4 3.Nc3 d6 4.Nxe4 g6 5.Bd3.
5...Nf6 6.Ng5 Nc6
7.Nxh7!? Nxh7? 8.Bxg6+ Kd7 9.Qg4+ e6
10.d5 Ne5? 11.Qxe6# 1-0
While ecogoogling the other day, I found a funny YouTube video that presents a DDG trick for bullet (1 + 1 minute) games. The DDG game starts at 7:35.
ecogoogling googling chess openings, which are organized by ECO (Encyclopaedia of Chess Openings) codes; the term is derived from egogoogling
The trick that wins a piece goes as follows:
1.e4 e6 2.d4 d5 3.c4
"I am playing my Duhm gambit again and again against this French Defence", says the guy on the video.
3...dxe4 4.Nc3 Nf6 5.d5?!
"Only players about 2200 fall for this, and beneath, of course; it happens very often", he continues.
I briefly mentioned this trick move in the DDG News in 2003.
5...exd5 6.cxd5 Bb4??
6...c6! -/+ busts the trick, but is hard to find in a bullet game.
7.Qa4+ Nc6 8.bxc6 +-
