Queen's Pawn Game: Colle System
ECO D05
Move order
1. d4 d5 2. Nf3 Nf6 3. e3 e6 4. b3 c5 5. Bb2 Nc6
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. This entry tracks a longer branch in the opening tree. Use the diagram and SAN list to recognize the tabiya, then try the line against Maia to explore typical plans in practice.