BLACKMAR-DIEMER GAMBIT 
1.d4 d5 2.e4 dxe4 3.Nc3 Nf6 4.f3 (exf3 5.Nxf3 Bf5 6.Ne5)
This opening also sometimes goes by the name Tartakower-Gunderam Defence. While 5...Bf5 is a logical developing move, the bishop will often become a target of white. The centralized Knight on e5 provides the support white needs to play the g-pawn to the g4-square. It was my first time to play the Blackmar-Diemer Gambit (BDG) with the black pieces; against an opponent who plays the BDG regularly.
The complete text of the game analysis:
1.d4 Nf6 2.Nc3 d5 3.e4 dxe4 4.f3
With a different move-order we've reached the Blackmar-Diemer Gambit (BDG).
4...exf3 5.Nxf3 Bf5
A logical continuation that develops black's LSB and is the starting point of the BDG-Gunderam Defence.
The best move. White strives for early complications to justify his pawn sacrifice.
Knowing that white will play 7.g4, then 6...h5 is not a good answer, because of 7.Qf3 Qc8 8.Bc4 e6 9.Bg5 Be7 10.Nxf7 Bg4 (or 10...Rf8 11.Ne5 Ng4 12.Bxe7 Kxe7 13.Nxg4 Bxg4 14.Qe3 and white is clearly better.) 11.Qd3 Kxf7 12.h3 and white is clearly better.
White wastes no time attacking the bishop on f5. The direct 7.Qf3 is not good, because of 7...Qxd4 8.Qxb7 Qxe5+ 9.Be3 Be4 and black is clearly better.
At this point black has probably three choices:
 The immediately counterattack with 7...Ne4. For example: 8.Bb5+ (if 8.gxf5 Qh4+ 9.Ke2 Qf2+ 10.Kd3 Nc5+ 11.Kc4 a6 12.a4 b5+ 13.axb5+ Nxb5 14.Rxa1 15.Nxc7+ Kd8 16.Nb5
leaves us with an unclair position.) c6 9.0-0 Nxc3 10.bxc3 Bg6 11.Bd3 Bd6 12. Bxg6 hxg6 13.Nxf7 Bxh2+ 14.Kg2 Qd5+ 15.Qf3 and we've reached an unclear position.
 Reaching a similar position as in the Teichmann Defence, without the white pawn on h3, with 7...Bg6. For example: 8.Bg2 c6 9.h4 Bb4 10.0-0 Bxc3 11.bxc3 Nbd7 12.Nxd7 Qxd7 13.h5 Be4 14.h6 Bxg2 15.hxg7 Rg8. 16.Kxg2 and black is better.
 The somewhat odd move 7...Be4, the Stader Variation. In this variation black chooses to trade his Bishop for white's Knight in an open position.
Black chose for the latter (option 3).
8.Nxe4 Nxe4 9.Qf3
Attacking the black Knight on e4 and the f7-square (for mate).
A provocative move. There are two alternatives:
 9...Qh4+ 10.Kd1 Nf2+ 11.Ke2 Nxh1 12.Qxf7+ Kd8 13.Bg2 Be7 14.Qxg7 Qf2+ 15.Kd3 Re8 16.Bxb7 Qf1+ 17.Kc3 Qe1+ 18.Bd2 Qxa1 19.Nf7+ Kd7 20.Ne5+ Ke8 and a draw.
 9...Nd6 (A quieter response, but doesn't keep black out of trouble after 10.Bb5+ c6 11.0-0 Qc7 12.Ba4 f6 13.Nd3 Nd7 14.Nf4 e5 15.Ne6 Qa5 16.Bb3 and white is clearly better.
10.Qxf7+ Kd8 11.Qf4
The threat of 11...Bb4+ makes it necessary to avoid 12.c3 Nxc3.
11...Bb4+ 12.c3 g5
I don't know it black will enjoy 12...Bxc3+ 13.bxc3 Qxc3+ 14.Kd1 Qd4+ 15.Bd3 Nf2+ Ke2 where all the white pieces are out and black has difficulties to develop.
After 13...Bxc3+ 14.bxc3 Qxe5 15.Bg2 Nc5 1.Qxe5 Nd3+ 17.Ke2 Nxe5 18.Bxb7 and black will win the game. Or 13...Qxe3+ 14.Bxe3 Nxc3 15.Bd2 Nd5 16.Nf7+ and black wins the game.
The alternative is 14.cxb4 Nd7 15.Bg2 Nd6 16.Qxe5 Nxe5 17.Bxg5+ Kd7 and white is better I think.
Not good. Better is 14...Be7 defending the pawn on g5. White is now better.
The alternative is 15.cxb4 Nd6 16.Qxe5 Nxe5 17.Bxg5+ Kd7 and white is better.
A miscalculation on part of black costs him the game. Better is 15...Be7 and it's about equal.
16.Bxb7 Qxe3+ 17.Bxe3 Rb8 18.O-O-O+ Bd6 19.Bxg5 Ke7 20.Rhf1 Rhf8 21.Bc6 Rb6 22.Ba4 Rf7 23.h3 Be5
Losing in a lost position.
I think it was a nice game, where white demonstrates the power of the BDG. Unfortunally I was black. A small step for me (I learned something), but a giant step for the BDG!
Other blog's of mine on the BDG: