Nimzo-Larsen Attack

Played by Aron Nimzowitsch and later by Bent Larsen. White fianchettoes the queen’s bishop to aim along the long diagonal. Its most famous game is a loss: Boris Spassky beat Larsen in 17 moves at the 1970 USSR v Rest of the World match.

It is reached after a single move: 1. b3.

Black is to move and has 20 legal moves. Over the next four moves — two for each side — the game can branch into 215,255 different games. Those games reach 77,853 different positions: most positions can be reached in more than one way, 2.8 on average.

The Lichess opening list names 14 further lines after this position, such as Modern Variation (1... e5) and Classical Variation (1... d5).