English Opening:King's English Variation, Four Knights Variation

It is reached after 6 moves: 1. c4 e5 2. Nc3 Nf6 3. Nf3 Nc6. It is a line of the English Opening.

White is to move and has 28 legal moves. Over the next four moves — two for each side — the game can branch into 758,666 different games. Those games reach 258,987 different positions: most positions can be reached in more than one way, 2.9 on average.

The Lichess opening list names 17 further lines after this position, such as Fianchetto Line (4. g3) and Quiet Line (4. e3).

The same moves can be played in 18 different legal orders that all reach this position. For example 1. Nf3 e5 2. c4 Nf6 3. Nc3 Nc6, which starts as the Zukertort Opening.