White 99 vs Black 164

The two setups

White: setup #99 B Q N R N K R B

King on the f-file, rooks on d, g, queen on the b-file; one bishop starts in a corner; the knights start on central files. Castling follows the Chess960 rule: king and rook end on the classical squares. In ordinary symmetric play setup 99 gives White +0.17 (Morozov Balance Index, 400M nodes).

Black: setup #164 N B B R N K Q R

King on the f-file, rooks on d, h, queen on the g-file; no bishop starts in a corner; the knights start away from the centre. Castling follows the Chess960 rule: king and rook end on the classical squares. In ordinary symmetric play setup 164 gives White +0.39 (Morozov Balance Index, 400M nodes).

Why the pair is balanced

At the deepest rungs (400M, 800M, 1.6B nodes) the evaluation is exactly 0.00 each time, reaching search depth 60.

Admission rule: |cp| ≤ 5 at four budgets up to 4 billion nodes, no one-sided drift along the ladder, and confirmation by two independent engines — Berserk and Lc0 — each below its own median on symmetric positions.

The shallow rungs wandered between -31 and 0 cp before settling — a reminder that quick engine checks overstate imbalances, and why the ladder goes deep.

For comparison, in symmetric play setup 99 gives White +0.17 and setup 164 gives White +0.39: with both sides on the same rank the first move is worth something. In this pair Black's own setup absorbs that edge completely.

White is not forced into a single path: the best first move is b3, and 3 first moves are within 10 cp of it.

Along the engine's main line (30 moves) the evaluation stayed within ±17 cp the whole way: the balance holds as the pieces come out, not only on move one.

Engine self-play agrees: 10 games, White won 0, drawn 10, Black won 0 (White scored 50.0%).

Verification ladder

Nine independent searches of the starting position, each with a larger node budget. Evaluation in centipawns from White's point of view.

Deep verification

The search ladder reaches 1.6 billion nodes; admission needs a 4-billion rung and two further engines on top of that. Beyond even that, every pair was re-checked at budgets up to ten times larger and in thousands of self-play games. This section shows what each check returned for this pair.

This pair held exactly 0.00 up to 1 600 000 000 nodes.

Independent engines, run on the same position:

• Berserk 14: 0
• Lc0 0.32.1: -12

Independent confirmations: 2 of 3. An engine counts as confirming when its reading of the pair is closer to equality than its own reading of a typical symmetric Chess960 position (+10 for Berserk, +18 for Lc0). Where only one engine confirms, the pair is balanced according to that engine alone, and this page says so.

Own weight of each setup, measured against the classical array: White +129, Black +63, difference +66. A balanced pair needs White's setup to be weaker by about the price of the first move.

Extended self-play: 10 games, 0 White wins, 10 draws, 0 Black wins, White scored 50.0%.

Best first moves

The 3 best first moves for White, searched together at 400 000 000 nodes.

Main-line play-out

30 moves, 5 000 000 nodes per half-move. Largest |evaluation| 17 cp, mean 3.6 cp, final 0 cp.

Engine self-play

10 games at 500 000 nodes per move: White won 0, drawn 10, Black won 0 — White scored 50.0%. Average length 34.1 moves.

1. b3 f6 2. g3 c6 3. f4 d5 4. Nf3 Qf7 5. O-O O-O 6. Nd3 Nd6 7. Nf2 Qh5 8. e3 Nc7 9. Bg2 Rfe8 10. Nh4 Nf5 11. Bf3 Qf7 12. Nxf5 Bxf5 13. Rde1 Nb5 14. Qc1 e5 15. c4 Nd6 16. fxe5 fxe5 17. c5 e4 18. Be2 Nc8 19. Nh3 Qd7 20. Nf4 Bg4 21. Qd1 Bxe2 22. Rxe2 Bxf4 23. gxf4 Ne7 24. Rg2 Nf5 25. Bf6 Ra8 26. Qg4 g6 27. Be5 Rad8 28. Bf6 Ra8 29. Be5 Rad8 30. Kh1 d4 31. Qh3 dxe3 32. Rxg6+ hxg6 33. Qh8+ Kf7 34. Qf6+ Kg8 35. Qh8+ Kf7 36. Qf6+ Kg8

1. g3 d5 2. b3 h5 3. f4 Qh7 4. Ncd3 c6 5. c4 O-O 6. Nf3 Nac7 7. Nf2 Qxb1 8. Rxb1 Nd6 9. Rc1 f6 10. O-O Kf7 11. d3 Nf5 12. e4 dxe4 13. dxe4 Ne3 14. Rfe1 Ng4 15. c5 Na6 16. a3 e5 17. fxe5 Bxe5 18. b4 Bxa1 19. Rxa1 Nc7 20. e5 Nxf2 21. Kxf2 g5 22. exf6 Kxf6 23. Kg1 g4 24. Ne5 Be6 25. Re3 Rfe8 26. Rf1+ Kg7 27. Rfe1 Rd2 28. Nd3 Bf7 29. Rxe8 Nxe8 30. Ne5 Nc7 31. Nxf7 Kxf7 32. Bg2 Nb5 33. Rf1+ Ke6 34. Re1+ Kf6 35. Rf1+ Kg7 36. Re1 Kf6 37. Rf1+ Ke6 38. Re1+

Play it in the CH960 app

Open this page on a phone with the CH960 app installed, or find pair 99 / 164 in the app's encyclopedia, then choose how to play.

• Local game — two players on one device, with a clock.
• With a mentor — a clearly labelled training bot with hints, at your level.
• Challenge a friend — an online game by link; both players get the same pair, colours swap on rematch.

Play this pair against the computer, right here Play a friend

FEN (Shredder, castling rights by rook files): nbbrnkqr/pppppppp/8/8/8/8/PPPPPPPP/BQNRNKRB w DGdh - 0 1

Mirror twin (the same position mirrored): White 851 vs Black 798.