Queen's Pawn Game: Accelerated London System, Steinitz Countergambit, Morris Countergambit Accepted
ECO D00
Move order
1. d4 d5 2. Bf4 c5 3. e4 dxe4
Ideas
ECO D covers queen-pawn games and closed structures, including many Gambits and the Queen's Gambit complex. White builds a pawn center and keeps the position more closed than after 1. e4. The variation is defined by a short, recognizable move order. Use the diagram and SAN list to recognize the tabiya, then try the line against Maia to explore typical plans in practice.