Slav Defense

Black supports d5 with 2...c6 and keeps the light-squared bishop free. It has been a main line at the top level since the 1930s.

It is reached after 4 moves: 1. d4 d5 2. c4 c6.

White is to move and has 30 legal moves. Over the next four moves — two for each side — the game can branch into 788,556 different games. Those games reach 259,694 different positions: most positions can be reached in more than one way, 3 on average.

The Lichess opening list names 120 further lines after this position, such as Exchange Variation (3. cxd5) and Modern Line (3. Nf3).

The same moves can be played in 4 different legal orders that all reach this position. For example 1. c4 d5 2. d4 c6, which starts as the English Opening.