The Blackmar Diemer gambit is an exciting tactical opening which begins 1) d4 d5 2)e4.
White sacrifices a pawn but gains open lines and rapid development. If Black is not careful he can get caught up in a whirlwind attack. But Black has possibilities too....he is a pawn up from move 3 and if he knows what to do the struggle can become a balance between White's initiative and Black's material
There are ways of getting there by transposition for example from the Scandinavian 1) e4 d5 2 d4.
The opening is probably not completely sound but it leads to exciting, rich, tactical play which is great fun....and FUN is why most of us are here.
Club BDG was created to explore the possibilities of this wonderful opening which has many fans. To some it is almost a way of life (like the Siclian Dragon) If we can get enough people we can start a good forum and organise private Tournaments.
As a taster here is a classic from Emil Diemer who invented the BDG opening.