Flank openings

Colle System

1.d4 g6 2.Nf3 Bg7 3.e3 c5 4.Bd3 Qa5+

The Colle System starts with 1.d4 g6 2.Nf3 Bg7 3.e3 c5 4.Bd3 Qa5+ and is catalogued under ECO A40, in the flank openings half of the book. The catalog indexes 3 lines inside it, grouped into 3 named variations.

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Current setup

Move ideas

  1. 1.d4

    Takes central space with a protected pawn and frees the queen’s bishop.

    Idea: Build a stable center that supports a broad positional setup.

  2. 1g6

    Advances the g-pawn to gain kingside space and control new squares.

    Idea: Create useful wing space while keeping the central structure flexible.

  3. 2.Nf3

    Develops the knight to f3, bringing it into the game.

    Idea: Improve piece coordination and clear the back rank for castling and the rooks.

  4. 2Bg7

    Develops the bishop to g7, bringing it into the game.

    Idea: Improve piece coordination and clear the back rank for castling and the rooks.

  5. 3.e3

    Advances to e3 to claim central space and control nearby key squares.

    Idea: Give the pieces room to develop behind a durable central foothold.

  6. 3c5

    Advances the c-pawn to gain queenside space and control new squares.

    Idea: Create useful wing space while keeping the central structure flexible.

  7. 4.Bd3

    Develops the bishop to d3, bringing it into the game.

    Idea: Improve piece coordination and clear the back rank for castling and the rooks.

  8. 4Qa5+

    Repositions the queen to a5, where it influences a new part of the board, forcing the king to answer a check.

    Idea: Coordinate threats carefully while avoiding unnecessary tempi against the queen.

Book continuations

Waiting for Lichess game popularity.

0 moves
This is the end of the indexed line.

Named variations

Each line below is an indexed entry under Colle System. Open one to load it on the board and keep exploring from that position.

ECO groups openings by the structures they lead to, so these families tend to share plans with the Colle System.