White 266 vs Black 286
White starts from setup 266 (NRKNBBQR), Black from setup 286 (NRKNRBBQ). 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 #266 N R K N B B Q R
King on the c-file, rooks on b, h, queen on the g-file; no bishop starts in a corner; the knights start away from the centre. The king already stands on a castled square, so one of the castlings moves only the rook. In ordinary symmetric play setup 266 gives White +0.26 (Morozov Balance Index, 400M nodes).
Black: setup #286 N R K N R B B Q
King on the c-file, rooks on b, e, queen on the h-file; no bishop starts in a corner; the knights start away from the centre. The king already stands on a castled square, so one of the castlings moves only the rook. In ordinary symmetric play setup 286 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 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 shallow rungs agreed early: from 100 thousand to 128 million nodes the evaluation never left ±10 cp.
For comparison, in symmetric play setup 266 gives White +0.26 and setup 286 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.
The engine's first choice for White is f4; the alternatives are slightly weaker but keep the game level.
Along the engine's main line (30 moves) the evaluation stayed within ±14 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 | -6 | 1. Nc3 e5 2. e4 g6 3. f3 f5 4. O-O-O Nc6 |
| S1 | 500 000 | 19 | +2 | 1. f4 f5 2. Nc3 g6 3. g4 Bg7 4. Nb3 Nb6 |
| S2 | 2 000 000 | 29 | +10 | 1. f4 e5 2. fxe5 f6 3. Nc3 fxe5 4. O-O-O Nc6 |
| S3 | 8 000 000 | 34 | +6 | 1. f4 e5 2. fxe5 f6 3. Nc3 fxe5 4. e4 Nb6 |
| S4 | 32 000 000 | 38 | 0 | 1. f4 Nb6 2. Nc3 f6 3. O-O-O e5 4. e4 Nc6 |
| S5 | 128 000 000 | 48 | 0 | 1. f4 e5 2. fxe5 f6 3. Nc3 fxe5 4. e4 Nb6 |
| S6 | 400 000 000 | 50 | 0 | 1. f4 e5 2. fxe5 f6 3. Nc3 fxe5 4. e4 Nb6 |
| S7 | 800 000 000 | 54 | 0 | 1. f4 e5 2. fxe5 f6 3. Nc3 fxe5 4. e4 Nc6 |
| S8 | 1 600 000 000 | 56 | +2 | 1. f4 e5 2. fxe5 f6 3. Nc3 fxe5 4. e4 Nc6 |
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: 0
- Lc0 0.32.1: 0
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 +52, Black +122, difference -70. 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 | +10 | 44 | 1. f4 e5 2. fxe5 f6 3. Nc3 fxe5 4. e4 Nc6 5. Bf2 Nb6 |
| 2 | -15 | 44 | 1. Nc3 e5 2. e4 g6 3. O-O-O f5 4. f3 Nb6 5. Bf2 Nc6 |
| 3 | -16 | 44 | 1. Nb3 e5 2. e4 f5 3. f3 g6 4. Nc3 Nc6 5. O-O-O Nb6 |
Main-line play-out
30 moves, 5 000 000 nodes per half-move. Largest |evaluation| 14 cp, mean 2.4 cp, final -2 cp.
| # | White | cp | Black | cp |
|---|---|---|---|---|
| 1 | f4 | +8 | e5 | 0 |
| 2 | fxe5 | +5 | f6 | +4 |
| 3 | Nb3 | +8 | fxe5 | 0 |
| 4 | e4 | +3 | Nb6 | +5 |
| 5 | Nc3 | +6 | Nc6 | +5 |
| 6 | Bf2 | +6 | O-O-O | +8 |
| 7 | Bb5 | +8 | Be7 | +2 |
| 8 | O-O-O | 0 | g6 | 0 |
| 9 | Kb1 | +13 | Rf8 | +14 |
| 10 | Be3 | 0 | Qg7 | 0 |
| 11 | h4 | -4 | h6 | 0 |
| 12 | g4 | 0 | Kb8 | -2 |
| 13 | Bxc6 | -3 | dxc6 | -7 |
| 14 | Ne2 | 0 | Nc8 | 0 |
| 15 | h5 | 0 | g5 | 0 |
| 16 | Ng3 | +3 | Qf6 | +2 |
| 17 | Nf5 | +12 | b6 | 0 |
| 18 | d4 | 0 | Kb7 | 0 |
| 19 | Qg2 | 0 | Bd6 | 0 |
| 20 | d5 | -3 | cxd5 | 0 |
| 21 | exd5 | 0 | Ne7 | 0 |
| 22 | Nxd6+ | 0 | Rxd6 | 0 |
| 23 | Rhf1 | 0 | Qg7 | 0 |
| 24 | c4 | 0 | Rxf1 | 0 |
| 25 | Qxf1 | 0 | Qf6 | 0 |
| 26 | Bd2 | -4 | c6 | 0 |
| 27 | Bb4 | 0 | Qxf1 | 0 |
| 28 | Rxf1 | 0 | Rd7 | 0 |
| 29 | d6 | 0 | Nc8 | -5 |
| 30 | c5 | 0 | Bxb3 | -2 |
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 38.8 moves.
Sample game 1 (1/2-1/2)
1. f4 Nb6 2. Nc3 Nc6 3. O-O-O f5 4. d4 g6 5. g4 Nb4 6. e3 N4d5 7. Qf2 Nc4 8. Bxc4 Nxc3 9. Bxc3 Bxc4 10. d5 Qg8 11. gxf5 gxf5 12. Rhg1 Qf7 13. Qd2 b6 14. Nb3 a5 15. Qd4 Be2 16. Rd2 Ba6 17. Rg3 e6 18. Rd1 Bb7 19. d6 Bxd6 20. Qc4 Qf8 21. Bg7 Qe7 22. Nd4 Ra8 23. Nb5 Bc6 24. Nxd6+ cxd6 25. Qc3 e5 26. Qd3 exf4 27. exf4 Rg8 28. Bd4 Rxg3 29. hxg3 Be4 30. Qb5 d5 31. Qxb6 Qb4 32. Rd2 Qxb6 33. Bxb6 Ra6 34. Bf2 Rh6 35. b3 Kb7 36. Kb2 Rh2 37. a4 Rh3 38. Ka3 h5 39. c3 h4 40. gxh4 Rxc3
Sample game 2 (1/2-1/2)
1. f3 Nb6 2. Nc3 Nc6 3. d4 d5 4. O-O-O e5 5. Nb3 O-O-O 6. dxe5 h5 7. Kb1 Qh6 8. Bd2 Qg6 9. e4 dxe4 10. fxe4 Nxe5 11. a4 f6 12. a5 Bxb3 13. axb6 axb6 14. Bb5 c6 15. Qxb6 Bxc2+ 16. Kxc2 cxb5 17. Rhe1 Rd6 18. Qxb5 Red8 19. Re2 Nc6 20. Qc4 Qg4 21. Nb5 Rd5 22. Na7+ Kc7 23. h3 Rc5 24. hxg4 Rxc4+ 25. Kb3 Rxd2 26. Rexd2 Rb4+ 27. Kc2 Nxa7 28. Rd8 Bc5 29. gxh5 Kb6 30. R1d7 Nc6 31. Re8 Bd4 32. Rxg7 Rxb2+ 33. Kd3 Rb3+ 34. Kc2 Rc3+ 35. Kd2 Ra3 36. Kc2 Rc3+ 37. Kd2 Ra3 38. Kc2
Play it in the CH960 app
Open this page on a phone with the CH960 app installed, or find pair 266 / 286 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): nrknrbbq/pppppppp/8/8/8/8/PPPPPPPP/NRKNBBQR w BHbe - 0 1
Mirror twin (the same position mirrored): White 597 vs Black 580.
Current place in the live balance rating: 182.