Grünfeld Defense

Introduced by Ernst Grünfeld in 1922. Black lets White build a centre after ...d5 and attacks it with pieces; it was one of Garry Kasparov’s main weapons.

It is reached after 6 moves: 1. d4 Nf6 2. c4 g6 3. Nc3 d5.

White is to move and has 33 legal moves. Over the next four moves — two for each side — the game can branch into 1,045,639 different games. Those games reach 347,593 different positions: most positions can be reached in more than one way, 3 on average.

The Lichess opening list names 54 further lines after this position, such as Exchange Variation (4. cxd5 Nxd5) and Brinckmann Attack (4. Bf4).

The same moves can be played in 18 different legal orders that all reach this position. For example 1. c4 Nf6 2. d4 g6 3. Nc3 d5, which starts as the English Opening.