Catalan Opening

Named after Catalonia: Savielly Tartakower introduced it at the Barcelona tournament of 1929. White fianchettoes the king’s bishop against Black’s queenside.

It is reached after 5 moves: 1. d4 Nf6 2. c4 e6 3. g3.

Black is to move and has 28 legal moves. Over the next four moves — two for each side — the game can branch into 767,252 different games. Those games reach 251,946 different positions: most positions can be reached in more than one way, 3 on average.

The Lichess opening list names 44 further lines after this position, such as Bogo-Indian Defense, Retreat Variation (3... Bb4+ 4. Bd2 Be7 5. Bg2 d5 6. Nf3) and Benoni Defense, Fianchetto Variation (3... c5 4. d5 exd5 5. cxd5 d6 6. Nc3 g6 7. Bg2 Bg7 8. Nf3 O-O).

The same moves can be played in 12 different legal orders that all reach this position. For example 1. c4 Nf6 2. d4 e6 3. g3, which starts as the English Opening.