The Dreaded BDG

Why do gambits like the Blackmar-Diemer and the Smith-Morra look so threatening
to average players, but get so little respect from masters?  The answer has
something to do with the familiarity of gambit play.  If you don't defend
gambits very often, you may tend to just clutch your pawn and huddle.  Instead,
you should exercise your whole brain, just as you do in even positions.
Tactical alertness and willingness to try unconventional ideas are especially
important.

White: Rob Nicholson
Black: Don Meigs
Wild Card Open, July 2001, Round 3
Blackmar-Diemer Gambit

 1 d4 Nf6
 2 Nc3 d5
 3 e4 de4
 4 f3 ef3
 5 Nf3 Bg4

   5 ... g6 and 5 ... e6 are also good choices.

 6 Bf4?!

   After the usual 6 h3, there can follow 6 ... Bxf3 7 Qxf3 c6 8 Be3 e6
   9 Bd3, or 6 ... Bh5 7 g4 Bg6 8 Ne5, with some (but not necessarily enough)
   compensation for the pawn in either case.

 6 ... c6
 7 Bc4

   Black can now play 7 ... Bxf3, and White can't reply 8 Qxf3 because of
   simply 8 ... Qxd4.  So 8 gxf3 is necessary, but White's new weaknesses and
   lack of any pressure on the f-file are devastating.  This is why White had
   to play 6 h3.

 7 ... e6?!
 8 0-0 Bd6
 9 Qd2 Bf3

   White's knight is going to be strong on e5, especially in conjunction with
   the half-open f-file, so Black is correct to chop it off.  But he should
   follow up by chopping off the black-squared bishop.

10 Rf3 Qe7?
11 Re1 0-0
12 Bg5!

   Getting out of this bind is going to cost Black.  If 12 ... h6?
   13 Bxf6 gxf6 14 Qxh6 will force mate.

12 ... Nbd7
13 Rh3

   Now 13 ... h6 is answered by 14 Bxh6! gxh6 15 Qxh6, again forcing mate.

13 ... Rfc8
14 Bd3 Qe8
15 Rf1 Kf8!

   Cold-blooded defense.

16 Bh7 Bb4
17 Bd3 Ke7??

   17 ... Bxc3 first was necessary.

   Diagram:  r1r1q3/pp1nkpp1/2p1pn2/6B1/1b1P4/2NB3R/PPPQ2PP/5RK1

18 Nd5+!

   Crushing.

18 ... cd5
19 Qb4+ Kd8
20 Bb5 Qf8
21 Qa4 Nb6
22 Rf6! gf6
23 Bf6+ Kc7
24 Rc3+ Nc4
25 Bc4 dc4
26 Rc4+ Kd6
27 Qb4+ Kd5
28 Qb5+ 

   Even quicker was 28 Qxb7+, so that if 28 ... Kxc4 29 Qb3 mate, or
   28 ... Kd6 29 Be5 mate.

28 ... Ke4

   28 ... Kd6 would have lost to 29 Be5+ Kd7 (or Ke7) 30 Qxb7+, etc.

29 Qe5# 1-0