White 27 vs Black 43
White starts from setup 27 (NQNRBKRB), Black from setup 43 (NNQRBKRB). In the encyclopedia since 2026-10-03: neither side starts better.
|cp| ≤ 5 at 400M · 800M · 1.6B · 4B nodes, two independent engines agree
The two setups
White: setup #27 N Q N R B 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 away from the centre. Castling follows the Chess960 rule: king and rook end on the classical squares. In ordinary symmetric play setup 27 gives White +0.27 (Morozov Balance Index, 400M nodes).
Black: setup #43 N N Q R B K R B
King on the f-file, rooks on d, g, queen on the c-file; one 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 43 gives White +0.15 (Morozov Balance Index, 400M nodes).
Why the pair is balanced
At the deepest rungs (400M, 800M, 1.6B nodes) the evaluation never left ±2 centipawns of equality, reaching search depth 58.
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 agreed early: from 100 thousand to 128 million nodes the evaluation never left ±14 cp.
For comparison, in symmetric play setup 27 gives White +0.27 and setup 43 gives White +0.15: 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 2 first moves are within 10 cp of it.
Along the engine's main line (14 moves) the evaluation stayed within ±12 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.
| Stage | Nodes | Depth | Eval, cp | Main line |
|---|---|---|---|---|
| S0 | 100 000 | 15 | +14 | 1. c4 O-O 2. Nc2 c6 3. d4 d5 4. Bb4 Qc7 |
| S1 | 500 000 | 17 | +5 | 1. d4 Nb6 2. Nab3 O-O 3. O-O Nc4 4. Nd2 Nxd2 |
| S2 | 2 000 000 | 27 | 0 | 1. d4 g6 2. O-O d6 3. c4 b5 4. g3 Nb6 |
| S3 | 8 000 000 | 31 | +10 | 1. d4 g6 2. O-O Nb6 3. g3 d5 4. Nab3 O-O |
| S4 | 32 000 000 | 39 | +6 | 1. d4 g6 2. O-O d5 3. g3 Nb6 4. Nab3 O-O |
| S5 | 128 000 000 | 45 | 0 | 1. d4 g6 2. O-O Nb6 3. g3 d5 4. Nab3 O-O |
| S6 | 400 000 000 | 50 | -2 | 1. d4 g6 2. c4 d6 3. O-O b5 4. g3 Nb6 |
| S7 | 800 000 000 | 56 | 0 | 1. d4 Nb6 2. b3 g6 3. d5 e6 4. c4 O-O |
| S8 | 1 600 000 000 | 58 | 0 | 1. d4 Nb6 2. b3 g6 3. d5 e6 4. c4 O-O |
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.
| Nodes | Eval, cp |
|---|---|
| 4 000 000 000 | not checked |
| 8 000 000 000 | not checked |
| 16 000 000 000 | not checked |
This pair held exactly 0.00 up to 1 600 000 000 nodes.
Independent engines, run on the same position:
- Berserk 14: -5
- Lc0 0.32.1: +4
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 +30, Black +77, difference -47. 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.
| # | Eval, cp | Depth | Main line |
|---|---|---|---|
| 1 | +13 | 45 | 1. d4 g6 2. c4 d6 3. O-O c5 4. dxc5 dxc5 5. Rxd8 Qxd8 |
| 2 | +3 | 45 | 1. c3 g6 2. d4 c5 3. g3 Nb6 4. Nc2 d5 5. Nd3 c4 |
| 3 | 0 | 45 | 1. c4 c5 2. d4 cxd4 3. Qxh7 Nb6 4. c5 Qxc5 5. Nab3 Qc8 |
Main-line play-out
14 moves, 5 000 000 nodes per half-move. Largest |evaluation| 12 cp, mean 3.6 cp, final 0 cp.
| # | White | cp | Black | cp |
|---|---|---|---|---|
| 1 | d4 | +12 | Nb6 | +2 |
| 2 | O-O | -2 | g6 | -10 |
| 3 | g3 | -3 | d5 | 0 |
| 4 | Nab3 | -1 | O-O | +4 |
| 5 | Nd3 | 0 | Bd7 | +2 |
| 6 | Bd2 | +7 | Bf5 | +8 |
| 7 | Qc1 | +5 | Nc4 | +10 |
| 8 | Bf4 | +6 | b6 | +6 |
| 9 | Bg2 | 0 | Bg7 | 0 |
| 10 | Bh6 | 0 | Bxh6 | +2 |
| 11 | Qxh6 | +6 | Be4 | +5 |
| 12 | Bh3 | +8 | Bf5 | +1 |
| 13 | Bg2 | 0 | Be4 | 0 |
| 14 | Bh3 | 0 | Bf5 | 0 |
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 39.2 moves.
Sample game 1 (1/2-1/2)
1. O-O c5 2. c3 Nb6 3. d4 O-O 4. Qe4 cxd4 5. Qxe7 Na4 6. Qa3 dxc3 7. Bxc3 Nxc3 8. bxc3 g6 9. Qxa7 Bxc3 10. Nc2 d5 11. g3 Bc6 12. Nd4 Bd7 13. Ncb3 Bh3 14. Bg2 Bxg2 15. Kxg2 Nc6 16. Nxc6 Qxc6 17. Qc5 Qxc5 18. Nxc5 d4 19. Rd3 Rfe8 20. e3 dxe3 21. Rxc3 e2 22. Re1 Rd1 23. Nd3 Rd8 24. Rxe2 R1xd3 25. Rc7 Ra3 26. Ree7 Rf8 27. Rxb7 Rxa2 28. g4 h5 29. gxh5 gxh5 30. Re5 h4 31. Rg5+ Kh7 32. Rh5+ Kg7 33. Rxh4 Ra6 34. Rf4 Kg6 35. Kg3 Ra3+ 36. f3 Ra6 37. Rfb4 Kh7 38. h4 Rg6+ 39. Kf2 Rf6 40. R7b6 Rg6 41. Rb7 Rf6 42. Ra7 Rc8 43. Kg3 Rc5 44. Rba4 Rg6+ 45. Rg4 Kg7 46. Ra6 Rxg4+ 47. fxg4 Rc3+ 48. Kf4 Rc4+ 49. Kf5 Rc5+ 50. Kf4
Sample game 2 (1/2-1/2)
1. O-O c5 2. g3 Nc7 3. c3 O-O 4. d4 cxd4 5. cxd4 d5 6. Nd3 g6 7. e3 Bd7 8. Bg2 Bf5 9. Qc2 Qd7 10. Qe2 b6 11. Nc2 a5 12. b4 a4 13. Nf4 Rc8 14. Na3 Rfe8 15. f3 e5 16. dxe5 Bxe5 17. e4 Bxf4 18. gxf4 Qc6 19. b5 Qc5+ 20. Qf2 Qxa3 21. exf5 Nxb5 22. fxg6 hxg6 23. f5 Qc5 24. fxg6 fxg6 25. Qxc5 Rxc5 26. Bf2 Rc2 27. Rxd5 Nc3 28. Rg5 Ne2+ 29. Kh1 Nf4 30. Rg4 Nxg2 31. Rxg6+ Kh7 32. Rxg2 Ree2 33. Rfg1 Rxf2 34. Rg7+ Kh6 35. R1g6+ Kh5 36. Rg5+ Kh6 37. R5g6+ Kh5 38. Rg5+ Kh6
Play it in the CH960 app
Open this page on a phone with the CH960 app installed, or find pair 27 / 43 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): nnqrbkrb/pppppppp/8/8/8/8/PPPPPPPP/NQNRBKRB w DGdg - 0 1
Mirror twin (the same position mirrored): White 929 vs Black 913.