Because of the small amount of the known games - at least to me - I cannot give any comprehensive opening theory. Later on, if I just get more games, I will try to do that. To begin with, I have selected herein five DDG games of mine, which all transpose to the most common variation 3. -dxe4 4. Nc3 Nf6 5. f3, and four of them also continue 5. -exf3 6. Nxf3. In my analysis, I have tried to pick the sharpest lines bubbling under the surface. Hopefully BDGers find fresh ideas from these games; after all, 1. d4 d5 2. e4 e6 can also be met by 3. c4.
The main ideas behind 3. c4 as I see them are as follows. First, it allows White to play Bc2-Qd3 to attack h7, which has proven lethal if Black dares castle on the King-side. Second, if Black plays c5, White usually can advance to d5. As a whole, c4 makes the DDG different from the BDG.
Moreover, the DDG has many elements already familiar to BDGers. By playing f3, White tries to get a half-open f-line, and after O-O, his Rook is ready to attack. If Black plays Bb4, White usually gets a pair of Bishops. Bg5 is often decisive in pinning Nf6. And finally, as all gambiteers know, the very idea is to create sharp mating attacks, and avoid long endgames.
The greedy Black tries to win the d5 pawn with b5-b4, but White has
a neat way to defend it. This is the first non-blitz DDG of mine.
Jyrki Heikkinen - Lauri Aapola, Tampere 1990.
This is a rare DDG in that White exchanges Queens to get a better
middle game. Fortunately, the game ends quickly, though.
Jyrki Heikkinen - Pasi Korhonen, Vantaa 1991.
Jyrki Heikkinen - Matti Pulli, Vantaa 1991.
Here Black wins another pawn, and castles on the Queen-side.
Jyrki Heikkinen - Tero Kokkila, Espoo 1991.