White 202 vs Black 657
White starts from setup 202 (QNRKBBNR), Black from setup 657 (BRNBKRNQ). 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 #202 Q N R K B B N R
King on the d-file, rooks on c, h, queen on the a-file; no 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 202 gives White +0.30 (Morozov Balance Index, 400M nodes).
Black: setup #657 B R N B K R N Q
King on the e-file, rooks on b, f, queen on the h-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 657 gives White +0.23 (Morozov Balance Index, 400M nodes).
Why the pair is balanced
At the deepest rungs (400M, 800M, 1.6B nodes) the evaluation never left ±4 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 shallow rungs wandered between -17 and +15 cp before settling — a reminder that quick engine checks overstate imbalances, and why the ladder goes deep.
For comparison, in symmetric play setup 202 gives White +0.30 and setup 657 gives White +0.23: 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 a4, and 2 first moves are within 10 cp of it.
Along the engine's main line (30 moves) the largest swing was 53 cp (around move 15), ending at -11 cp — the position stays playable for both sides.
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.
| Stage | Nodes | Depth | Eval, cp | Main line |
|---|---|---|---|---|
| S0 | 100 000 | 14 | +15 | 1. a4 b6 2. h4 f5 3. f3 Nd6 4. O-O-O |
| S1 | 500 000 | 19 | -4 | 1. a4 a6 2. f3 f5 3. Nc3 g5 4. e4 Nd6 |
| S2 | 2 000 000 | 21 | -10 | 1. a4 a6 2. f3 f5 3. Nc3 Nf6 4. h4 e6 |
| S3 | 8 000 000 | 28 | -17 | 1. a4 f5 2. h4 Nf6 3. e3 g6 4. Nh3 e6 |
| S4 | 32 000 000 | 32 | -12 | 1. a4 e6 2. h4 g6 3. e3 f5 4. c4 Nf6 |
| S5 | 128 000 000 | 37 | +4 | 1. a4 e6 2. Nc3 g6 3. e3 Nf6 4. f3 O-O |
| S6 | 400 000 000 | 44 | 0 | 1. a4 g5 2. Nc3 e6 3. O-O-O a6 4. e4 Nge7 |
| S7 | 800 000 000 | 48 | 0 | 1. a4 g5 2. Nc3 e6 3. O-O-O a6 4. e4 f5 |
| S8 | 1 600 000 000 | 50 | -4 | 1. a4 g5 2. Nc3 e6 3. O-O-O a6 4. e4 b5 |
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: +4
- Lc0 0.32.1: -10
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 0, Black +40, difference -40. 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.
| # | Eval, cp | Depth | Main line |
|---|---|---|---|
| 1 | -5 | 38 | 1. a4 g5 2. Nc3 e6 3. O-O-O f5 4. d4 Nf6 5. e3 a6 |
| 2 | -7 | 38 | 1. h4 b5 2. h5 f5 3. e3 e6 4. b4 a6 5. a4 Bf6 |
| 3 | -20 | 37 | 1. c4 g5 2. e3 e6 3. Nc3 a6 4. a4 b6 5. d4 Nge7 |
Main-line play-out
30 moves, 5 000 000 nodes per half-move. Largest |evaluation| 53 cp, mean 27.1 cp, final -11 cp.
| # | White | cp | Black | cp |
|---|---|---|---|---|
| 1 | a4 | -22 | g5 | -13 |
| 2 | O-O-O | -3 | a6 | 0 |
| 3 | d4 | -20 | b5 | -32 |
| 4 | e3 | -30 | Qg7 | -40 |
| 5 | Nf3 | -33 | Nf6 | -32 |
| 6 | axb5 | -40 | axb5 | -41 |
| 7 | Ne5 | -35 | c6 | -41 |
| 8 | f3 | -45 | d6 | -38 |
| 9 | Nd3 | -28 | O-O | -41 |
| 10 | e4 | -45 | h5 | -36 |
| 11 | b3 | -31 | e6 | -39 |
| 12 | h4 | -38 | g4 | -27 |
| 13 | Be2 | -25 | Nb6 | -33 |
| 14 | Bc3 | -43 | Be7 | -49 |
| 15 | Rhf1 | -15 | Rfc8 | -53 |
| 16 | Nd2 | -37 | Bb7 | -22 |
| 17 | fxg4 | -33 | Ra8 | -20 |
| 18 | Qb2 | -29 | Nxg4 | -34 |
| 19 | Bxg4 | -37 | hxg4 | -34 |
| 20 | Kb1 | -25 | f5 | -32 |
| 21 | exf5 | -24 | exf5 | -20 |
| 22 | Rxf5 | -20 | Nd5 | -19 |
| 23 | Rdf1 | -17 | Rf8 | -23 |
| 24 | Rxf8+ | -17 | Rxf8 | -19 |
| 25 | Rxf8+ | -26 | Bxf8 | -17 |
| 26 | Ne4 | -18 | Qe7 | -14 |
| 27 | Ng3 | -17 | Qxh4 | -20 |
| 28 | Be1 | -14 | Qg5 | -18 |
| 29 | Qa1 | -14 | Qe3 | -11 |
| 30 | Qa7 | -15 | Bc8 | -11 |
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 50.9 moves.
Sample game 1 (1/2-1/2)
1. c4 g5 2. f3 a6 3. Nc3 f5 4. e3 e6 5. Qb1 Nf6 6. Qc2 Qg7 7. a4 g4 8. Bg3 O-O 9. Nge2 Kh8 10. O-O-O b6 11. Rg1 Nd6 12. h3 b5 13. cxb5 axb5 14. Bxd6 cxd6 15. axb5 g3 16. Kb1 Rc8 17. Qa4 e5 18. d4 Nd5 19. Nxd5 Bxd5 20. Nc3 Bf7 21. f4 Re8 22. Bd3 Bb6 23. Rge1 Ra8 24. Qb4 Rec8 25. fxe5 dxe5 26. Bxf5 Rc4 27. Qb3 exd4 28. exd4 d5 29. Bd3 Rxd4 30. Re7 Qf6 31. Rxf7 Qxf7 32. Ne2 Rda4 33. Qc3+ Qg7 34. Qc6 Rb8 35. Nc3 Rf4 36. Qxd5 Rd8 37. Qc6 Rf6 38. Qe4 Rd4 39. Qe8+ Rf8 40. Qc6 Rf6 41. Qe8+ Rf8 42. Qc6 Rf6
Sample game 2 (1/2-1/2)
1. c4 f5 2. h4 Nf6 3. h5 a6 4. e3 Qg8 5. b3 e6 6. Nf3 Qf7 7. Ne5 Qe7 8. h6 g5 9. d4 b5 10. Nd3 bxc4 11. bxc4 Nb6 12. f3 O-O 13. Nd2 Qf7 14. Bf2 d6 15. Rb1 Be7 16. Be2 Rfe8 17. Rb3 Qg6 18. Qc1 Rec8 19. Qc2 a5 20. Rb5 Bc6 21. Rxa5 Ra8 22. Rxa8 Rxa8 23. Ke1 Bf8 24. a3 Ba4 25. Qb2 Be8 26. Qb3 Ba4 27. Qb2 Bd7 28. Bg3 Nh5 29. Bf2 Nf6 30. Qb3 Bc6 31. Bg3 Nh5 32. Bf2 Nf6 33. Bg3 Nh5 34. Bf2
Play it in the CH960 app
Open this page on a phone with the CH960 app installed, or find pair 202 / 657 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): brnbkrnq/pppppppp/8/8/8/8/PPPPPPPP/QNRKBBNR w CHbf - 0 1
Mirror twin (the same position mirrored): White 661 vs Black 203.