Queen's Pawn Game:Colle System

Named after the Belgian master Edgard Colle: White builds a pyramid with e3, c3 and Bd3 and aims to break with e4.

It is reached after 5 moves: 1. d4 d5 2. Nf3 Nf6 3. e3. It is a line of the Queen's Pawn Game.

Black is to move and has 29 legal moves. Over the next four moves — two for each side — the game can branch into 828,014 different games. Those games reach 278,186 different positions: most positions can be reached in more than one way, 3 on average.

The Lichess opening list names 11 further lines after this position, such as Anti-Colle (3... Bf5) and Grünfeld Formation (3... g6 4. Bd3 Bg7).

The same moves can be played in 12 different legal orders that all reach this position. For example 1. Nf3 d5 2. d4 Nf6 3. e3, which starts as the Zukertort Opening.