Chess960 starting positions vary in difficulty by a factor of three, with some configurations demanding significantly more cognitive effort than others.

Researchers analyzed all 960 possible starting positions using Stockfish 17.1. They introduced an information-based measure that quantifies how much a player must think to identify the best moves within the first ten moves. The gap between the simplest and most complex positions spans nearly 10 bits of information — equivalent to the difference between a forced move and a choice among two equally viable options on every turn.

Standard chess, position 518, ranks 47th in overall difficulty. A to H: rook, knight, bishop, queen, king, bishop, knight, rook. It’s neither exceptionally difficult nor exceptionally easy. However, standard chess ranks 91st in asymmetry. Black faces harder decisions than White in the opening. Only 9% of Chess960 positions have a more unbalanced cognitive load.

Position 226 produces the highest total complexity. A to H: bishop, knight, rook, queen, king, bishop, knight, rook. This configuration generates maximum strategic depth while maintaining near-perfect symmetry between players.

Position 198 is the most balanced. A to H: queen, knight, bishop, king, bishop, rook, knight, rook. Evaluation: +0.03 pawns, Asymmetry: -0.03 bits. Both metrics are effectively zero. This position differs from standard chess by one transposition: queen and rook swap on the A-file.

The study analyzed 70,150 online moves with timestamps. Positions where the chess engine shows two moves of nearly equal strength match up with longer thinking time. The information cost indicator, bits, predicts human decision-making.

Chess960, also known as Fischer Random Chess or Freestyle Chess, was proposed by World Champion Bobby Fischer in 1996 with Susan Polgar. The back-rank pieces are shuffled before each game under three rules: bishops on opposite colors, king between rooks, Black mirrors White. This produces 960 legal starting positions.

The first official FIDE Freestyle Chess World Championship will be held in Weissenhaus, Germany, from February 13 to 15, 2026. The event is governed by FIDE in collaboration with Freestyle Chess Operations GmbH, marking the first joint World Championship title in 960 format under a formal agreement.

Credit: Freestyle Chess