Pirc Defense:Austrian Attack

White builds the biggest possible pawn centre with f4, aiming to overrun Black before the counterattack comes.

It is reached after 7 moves: 1. e4 d6 2. d4 Nf6 3. Nc3 g6 4. f4. It is a line of the Pirc Defense.

Black is to move and has 31 legal moves. Over the next four moves — two for each side — the game can branch into 1,201,192 different games. Those games reach 391,465 different positions: most positions can be reached in more than one way, 3.1 on average.

The Lichess opening list names 7 further lines after this position, such as Ljubojevic Variation (4... Bg7 5. Bc4) and Dragon Formation (4... Bg7 5. Nf3 c5).

The same moves can be played in 144 different legal orders that all reach this position. For example 1. d4 d6 2. e4 Nf6 3. Nc3 g6 4. f4, which starts as the Queen's Pawn Game.