White 61 vs Black 284

The two setups

White: setup #61 N N R B Q K B R

King on the f-file, rooks on c, h, queen on the e-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 61 gives White +0.49 (Morozov Balance Index, 400M nodes).

Black: setup #284 N B R K N R B Q

King on the d-file, rooks on c, f, queen on the h-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 284 gives White +0.19 (Morozov Balance Index, 400M nodes).

Why the pair is balanced

At the deepest rungs (400M, 800M, 1.6B, 3.2B nodes) the evaluation never left ±2 centipawns of equality, reaching search depth 56.

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 same corridor is required at every deeper budget (8 G, 16 G) at which the pair has been evaluated.

The shallow rungs wandered between -5 and +24 cp before settling — a reminder that quick engine checks overstate imbalances, and why the ladder goes deep.

For comparison, in symmetric play setup 61 gives White +0.49 and setup 284 gives White +0.19: 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 d4, and 3 first moves are within 10 cp of it.

Along the engine's main line (27 moves) the evaluation stayed within ±18 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 8, Black won 2 (White scored 40.0%).

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 stays within the ±5 cp corridor up to 4 000 000 000 nodes.

Independent engines, run on the same position:

• Berserk 14: -4
• Lc0 0.32.1: +12

Independent confirmations: 3 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 +38, Black +33, difference +5. 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, 8 draws, 2 Black wins, White scored 40.0%.

Best first moves

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

Main-line play-out

27 moves, 5 000 000 nodes per half-move. Largest |evaluation| 18 cp, mean 3.1 cp, final 0 cp.

Engine self-play

10 games at 500 000 nodes per move: White won 0, drawn 8, Black won 2 — White scored 40.0%. Average length 64.2 moves.

1. f3 f5 2. Nb3 c6 3. c4 h5 4. Bf2 g5 5. d4 Nd6 6. c5 Nc4 7. Na5 Nxa5 8. Qxa5+ Nc7 9. Bc2 Qh6 10. Qd2 h4 11. Nc3 O-O-O 12. h3 Nd5 13. Nxd5 Bxd5 14. O-O-O Bf4 15. e3 Bc7 16. Kb1 Qf6 17. Qd3 Rde8 18. Rd2 a6 19. e4 fxe4 20. fxe4 Ba5 21. Re2 Bf7 22. Be3 Qg7 23. d5 Bh5 24. Rf2 Rxf2 25. Bxf2 Bc7 26. Bd4 Qg8 27. Bb3 Qh7 28. Ka1 Bg6 29. Re1 Bg3 30. Re3 e5 31. dxe6 dxe6 32. Bf6 Bf4 33. Re1 Qd7 34. Qxd7+ Kxd7 35. Bd1 Rf8 36. e5 Bd2 37. Re2 Bf4 38. Re1 Bd2 39. Re2 Ba5 40. a3 Bd3 41. Rf2 Bc4 42. b4 Bc7 43. Bf3 Bd5 44. Kb2 Bd8 45. Bg4 Bc7 46. Bf3 a5 47. Kc3 Bd8 48. Bg4 axb4+ 49. axb4 b6 50. Kd4 Be7 51. Bh5

1. d4 c6 2. f3 h5 3. c4 f5 4. Nb3 Nd6 5. c5 Nc4 6. N3d2 Nxb2 7. Bb3 b5 8. Rc2 Na4 9. Bf2 Nc7 10. O-O g5 11. Bxa4 bxa4 12. Nc3 h4 13. h3 g4 14. hxg4 fxg4 15. Bxh4 Bh7 16. Rc1 Ne6 17. e3 Bd3 18. f4 Ng7 19. g3 Bxf1 20. Nxf1 Nf5 21. Ne4 Nxh4 22. gxh4 g3 23. Nfxg3 Qxh4 24. Kg2 Bc7 25. Qe2 Qh7 26. Rb1 Rg8 27. Qd3 Qh5 28. Qc4 Qd5 29. Qxd5 cxd5 30. Nc3 e6 31. Kf3 Rb8 32. Rxb8+ Bxb8 33. Nxa4 Rh8 34. Nc3 Bc7 35. Nb5 Bb8 36. Nc3 Rh2 37. Nce2 d6 38. e4 dxe4+ 39. Nxe4 Kd7 40. Nf6+ Ke7 41. Ne4 Rh1 42. N4c3 Rh3+ 43. Ng3 dxc5 44. dxc5 Kd7 45. Ne4 Rh6 46. Ne2 Kc6 47. Nd4+ Kd5 48. Ne2 a5 49. Ng5 Ba7 50. c6 Kxc6 51. Ke4 Kb5 52. Nf3 Ka4 53. Ng5 Kb4 54. Kd3 Bc5 55. Nc1 a4 56. Ne2 Be7 57. Ne4 Rh3+ 58. Kc2 Ra3 59. Nc1 Re3 60. Nf2 Rc3+ 61. Kd2 Rc8 62. Nfd3+ Ka3 63. Kd1 Bf6 64. Kd2 Bc3+ 65. Ke3 Bb2 66. Nb3 Kxa2 67. Nbc5 a3 68. Nb7 Kb1 69. Nd6 Rc6 70. Ne4 Bc1+ 71. Nxc1 Rxc1 72. Nd2+ Kb2 73. Ne4 a2 74. f5 exf5 75. Nf2 Kb1

Play it in the CH960 app

Open this page on a phone with the CH960 app installed, or find pair 61 / 284 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): nbrknrbq/pppppppp/8/8/8/8/PPPPPPPP/NNRBQKBR w CHcf - 0 1

Mirror twin: White 904 vs Black 588 — a different position (castling squares are fixed), not evaluated by the search.

Current place in the live balance rating: 14.