Van't Kruijs Opening

Named after the 19th-century Dutch player Maarten van ’t Kruijs. A modest first move that frees the king’s bishop and can turn into many other openings one move later.

It is reached after a single move: 1. e3.

Black is to move and has 20 legal moves. Over the next four moves — two for each side — the game can branch into 402,988 different games. Those games reach 140,581 different positions: most positions can be reached in more than one way, 2.9 on average.

The Lichess opening list names 5 further lines after this position, such as Bouncing Bishop Variation (1... e5 2. Bc4 b5 3. Bb3) and Keoni-Hiva Gambit, Akahi Variation (1... e5 2. Nc3 Nf6 3. f4 exf4 4. Nf3).