White 263 vs Black 737
White starts from setup 263 (NRBKNQRB), Black from setup 737 (BRKBNNQR). In the encyclopedia since 2026-10-21: neither side starts better.
|cp| ≤ 5 at 400M · 800M · 1.6B · 4B nodes, two independent engines agree
The two setups
White: setup #263 N R B K N Q R B
King on the d-file, rooks on b, g, queen on the f-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 263 gives White +0.38 (Morozov Balance Index, 400M nodes).
Black: setup #737 B R K B N N Q R
King on the c-file, rooks on b, h, queen on the g-file; one bishop starts in a corner; the knights start on central files. The king already stands on a castled square, so one of the castlings moves only the rook. In ordinary symmetric play setup 737 gives White +0.17 (Morozov Balance Index, 400M nodes).
Why the pair is balanced
At the deepest rungs (400M, 800M, 1.6B nodes) the evaluation never left ±5 centipawns of equality, reaching search depth 50.
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 agreed early: from 100 thousand to 128 million nodes the evaluation never left ±12 cp.
For comparison, in symmetric play setup 263 gives White +0.38 and setup 737 gives White +0.17: 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 Nb3, and 2 first moves are within 10 cp of it.
Along the engine's main line (14 moves) the evaluation stayed within ±19 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 | +12 | 1. b3 b5 2. Bb2 c5 3. O-O-O Ne6 4. g3 Bxh1 |
| S1 | 500 000 | 18 | +2 | 1. b3 b5 2. f4 f5 3. c3 Nf6 4. Nac2 d6 |
| S2 | 2 000 000 | 25 | -1 | 1. Nb3 e5 2. d3 b6 3. e4 a5 4. Be3 f5 |
| S3 | 8 000 000 | 29 | +6 | 1. Nb3 e5 2. d3 b6 3. e4 f6 4. c3 a5 |
| S4 | 32 000 000 | 35 | +12 | 1. g3 e5 2. Nb3 f5 3. d4 exd4 4. e3 Nd6 |
| S5 | 128 000 000 | 42 | 0 | 1. Nb3 b6 2. d3 e5 3. e4 a5 4. g3 f5 |
| S6 | 400 000 000 | 44 | 0 | 1. Nb3 b6 2. f4 f5 3. d3 a5 4. a4 Nf6 |
| S7 | 800 000 000 | 47 | -5 | 1. Nb3 b6 2. d4 f5 3. Nd2 Ng6 4. Nd3 c5 |
| S8 | 1 600 000 000 | 50 | 0 | 1. g3 f5 2. Nb3 e5 3. d4 exd4 4. e3 Nd6 |
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 | +4 |
| 8 000 000 000 | not checked |
| 16 000 000 000 | not checked |
This pair stays within the ±5 cp corridor up to 4 000 000 000 nodes.
Independent engines, run on the same position:
- Berserk 14: 0
- Lc0 0.32.1: +17
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 +10, Black +53, difference -43. 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 | +12 | 44 | 1. Nb3 e5 2. g3 f5 3. d4 exd4 4. e3 Nd6 5. exd4 Ng6 |
| 2 | +3 | 43 | 1. g3 f5 2. Nb3 e5 3. d4 exd4 4. e3 Nd6 5. exd4 Ng6 |
| 3 | 0 | 43 | 1. d3 b6 2. Nb3 e5 3. e4 a5 4. g3 f5 5. Nd2 Qf7 |
Main-line play-out
14 moves, 5 000 000 nodes per half-move. Largest |evaluation| 19 cp, mean 2.1 cp, final 0 cp.
| # | White | cp | Black | cp |
|---|---|---|---|---|
| 1 | Nb3 | +6 | b6 | +19 |
| 2 | d3 | +19 | e5 | +8 |
| 3 | e4 | -1 | a5 | 0 |
| 4 | g3 | 0 | f5 | 0 |
| 5 | Nd2 | 0 | Qxa2 | 0 |
| 6 | b3 | +6 | a4 | 0 |
| 7 | c4 | 0 | axb3 | 0 |
| 8 | Rxb3 | 0 | Be7 | 0 |
| 9 | Nc2 | 0 | fxe4 | 0 |
| 10 | Ba3 | 0 | Bxa3 | 0 |
| 11 | Rxa3 | 0 | Qb2 | 0 |
| 12 | Rb3 | 0 | Qa2 | 0 |
| 13 | Ra3 | 0 | Qb2 | 0 |
| 14 | Rb3 | 0 | Qa2 | 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 42.5 moves.
Sample game 1 (1/2-1/2)
1. g3 e5 2. b4 f5 3. Nb3 Bf6 4. d3 Nd6 5. c4 e4 6. Bf4 b5 7. c5 Nc4 8. dxc4 bxc4 9. Na5 Qd5+ 10. Kc1 Ne6 11. Nc2 c3 12. Rb3 g5 13. Qh3 gxf4 14. Rd1 Ng5 15. Qh5 Qe5 16. gxf4 Qxf4+ 17. e3 Qe5 18. h4 Nf3 19. c6 dxc6 20. Bxf3 exf3 21. Nd4 c2 22. Rdd3 O-O-O 23. Rbc3 Rhg8 24. Qxf3 Qe4 25. Qxe4 fxe4 26. Rd2 Rg1+ 27. Kxc2 Bxh4 28. Naxc6 Bxc6 29. Rxc6 Rf1 30. Rh6 Bxf2 31. Ne6 Rxd2+ 32. Kxd2 Ra1 33. Rxh7 Rxa2+ 34. Kc3 Bxe3 35. Rxc7+ Kb8 36. Re7 Bf2 37. Nd4 e3 38. Nc2 Ra6 39. Nxe3 Ra3+ 40. Kd2 Rxe3
Sample game 2 (1/2-1/2)
1. b3 f5 2. g4 fxg4 3. Rxg4 e5 4. Ra4 b5 5. Rxa7 Bxh1 6. Qxh1 c6 7. c4 bxc4 8. Nac2 Qe6 9. Ba3 Ng6 10. Qf3 Nf6 11. Kc1 e4 12. Qg3 c3 13. Qxc3 Nf4 14. Kd1 Bb6 15. Ra4 Ng4 16. Nd4 Qg6 17. e3 Nd5 18. Qc4 Ne5 19. Qf1 Bxd4 20. Rxd4 Ra8 21. Ra4 Kc7 22. Bb2 Qf5 23. h3 Rxa4 24. bxa4 Ra8 25. Bxe5+ Qxe5 26. Qc4 Qh5+ 27. Kc2 Qe5 28. Kd1 Qh5+ 29. Kc2 Nf6 30. f3 exf3 31. Qf4+ d6 32. Nxf3 c5 33. Qc4 Qf5+ 34. Kc1 Qxf3 35. Qf7+ Kd8 36. Qf8+ Kc7 37. Qf7+ Kd8 38. Qf8+ Kc7
Play it in the CH960 app
Open this page on a phone with the CH960 app installed, or find pair 263 / 737 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): brkbnnqr/pppppppp/8/8/8/8/PPPPPPPP/NRBKNQRB w BGbh - 0 1
Mirror twin: White 594 vs Black 411 — a different position (castling squares are fixed), not evaluated by the search.