White 88 vs Black 266
White starts from setup 88 (NBNRBKRQ), Black from setup 266 (NRKNBBQR). In the encyclopedia since 2026-10-21: neither side starts better.
|cp| ≤ 5 at 400M · 800M · 1.6B · 4B nodes, two independent engines agree
How to play with different setups
White sets up the pieces by position No. 88, Black by position No. 266, mirrored on their own side; the pawns stand as usual.
Moves as usual: White starts; everything else follows the Chess960 rules.
The two setups
White: setup #88 N B N R B K R Q
King on the f-file, rooks on d, g, 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 88 gives White +0.35 (Morozov Balance Index, 400M nodes).
Black: 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).
Why the pair is balanced
At the deepest rungs (400M, 800M, 1.6B nodes) the evaluation never left ±1 centipawns of equality, reaching search depth 57.
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 -16 and +48 cp before settling — a reminder that quick engine checks overstate imbalances, and why the ladder goes deep.
For comparison, in symmetric play setup 88 gives White +0.35 and setup 266 gives White +0.26: 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 c4; the alternatives are slightly weaker but keep the game level.
Along the engine's main line (30 moves) the largest swing was 58 cp (around move 13), ending at +6 cp — the position stays playable for both sides.
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 | +48 | 1. d4 d5 2. g4 Nb6 3. c3 a5 4. e4 e6 |
| S1 | 500 000 | 15 | +4 | 1. d4 d5 2. g4 Nb6 3. c3 f6 4. e4 h5 |
| S2 | 2 000 000 | 21 | -16 | 1. c4 f6 2. b3 e5 3. Nc2 Bg6 4. h4 h5 |
| S3 | 8 000 000 | 28 | +8 | 1. c4 f6 2. b3 Bg6 3. Nc2 e5 4. h4 h5 |
| S4 | 32 000 000 | 33 | +13 | 1. c4 f6 2. b3 d5 3. cxd5 Qxd5 4. d4 Nb6 |
| S5 | 128 000 000 | 39 | 0 | 1. c4 f6 2. b3 e5 3. Nc2 d5 4. cxd5 Qxd5 |
| S6 | 400 000 000 | 49 | 0 | 1. c4 f6 2. b3 e5 3. Nc2 d5 4. cxd5 Qxd5 |
| S7 | 800 000 000 | 50 | +1 | 1. c4 f6 2. b3 e5 3. Nc2 d5 4. cxd5 Qxd5 |
| S8 | 1 600 000 000 | 57 | 0 | 1. c4 f6 2. b3 d5 3. cxd5 Qxd5 4. d4 e6 |
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 | 0 |
| 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: -2
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 +24, Black +52, difference -28. 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 | +7 | 39 | 1. c4 f6 2. b3 e5 3. Nc2 d5 4. cxd5 Qxd5 5. d4 exd4 |
| 2 | -20 | 39 | 1. d4 f6 2. b3 e5 3. dxe5 fxe5 4. c4 Ne6 5. g3 O-O-O |
| 3 | -27 | 38 | 1. h4 Nb6 2. d4 d5 3. c3 Nc6 4. e4 O-O-O 5. exd5 Nxd5 |
Main-line play-out
30 moves, 5 000 000 nodes per half-move. Largest |evaluation| 58 cp, mean 17.5 cp, final +6 cp.
| # | White | cp | Black | cp |
|---|---|---|---|---|
| 1 | c4 | +2 | f6 | +11 |
| 2 | b3 | +14 | e5 | +19 |
| 3 | Nc2 | +25 | Bg6 | +22 |
| 4 | h4 | +22 | h5 | +20 |
| 5 | O-O | +27 | Ne6 | +25 |
| 6 | f3 | +23 | c5 | +18 |
| 7 | Qh2 | +20 | O-O-O | +14 |
| 8 | e4 | +15 | Nac7 | +10 |
| 9 | Ne3 | +7 | Nd4 | +10 |
| 10 | Nd5 | +21 | Kb8 | +23 |
| 11 | b4 | +56 | cxb4 | +43 |
| 12 | Nb3 | +52 | Nxb3 | +55 |
| 13 | axb3 | +52 | Bd6 | +58 |
| 14 | Ne3 | +56 | Bc5 | +37 |
| 15 | d4 | +37 | Bxd4 | +36 |
| 16 | Rxd4 | +31 | exd4 | +38 |
| 17 | Nc2 | +27 | Qe6 | +21 |
| 18 | Bg3 | +31 | d6 | +17 |
| 19 | Nxb4 | +23 | Qd7 | +8 |
| 20 | Kh1 | +6 | f5 | 0 |
| 21 | exf5 | +1 | Bxf5 | 0 |
| 22 | Bxf5 | +3 | Qxf5 | 0 |
| 23 | Bxd6 | 0 | Rxd6 | 0 |
| 24 | Qxd6 | +2 | Qf8 | +1 |
| 25 | Qxf8+ | 0 | Rxf8 | 0 |
| 26 | Nd3 | 0 | Re8 | 0 |
| 27 | Nf4 | +3 | Re3 | 0 |
| 28 | Nxh5 | 0 | Ne6 | 0 |
| 29 | b4 | 0 | Kc7 | 0 |
| 30 | Rd1 | +1 | Kd6 | +6 |
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 43.9 moves.
Sample game 1 (1/2-1/2)
1. d4 f6 2. e4 e5 3. c3 Nf7 4. Nc2 d5 5. exd5 Nb6 6. b3 Nxd5 7. c4 Nf4 8. h4 Bd7 9. Bc3 O-O-O 10. g3 Ne6 11. d5 Nc5 12. Ne3 Kb8 13. Nd3 Nxd3 14. Bxd3 g6 15. O-O-O f5 16. Kb1 Bg7 17. f3 Nd6 18. Rge1 b6 19. Bf1 f4 20. Nc2 fxg3 21. Qg1 Qf7 22. Qxg3 Rhe8 23. Bh3 Qf8 24. a4 a5 25. Bb2 Bf5 26. Bxf5 Qxf5 27. h5 Qxh5 28. Rh1 Qf5 29. Rxh7 Bf8 30. Qh3 g5 31. Bc1 Re7 32. Qxf5 Nxf5 33. Rh8 Ree8 34. Rh5 Bc5 35. Re1 Bf2 36. Bxg5 Rc8 37. Rd1 Rf8 38. Rh3 Rce8 39. b4 Rg8 40. Bd2 Nd6 41. bxa5 bxa5 42. Be3 Rg2 43. Bxf2 Rxf2 44. Na3 Ka7 45. Rh7 Rf8 46. Rxc7+ Kb8 47. Rc6 R8xf3 48. Nb5 Ne4 49. Ka1 Nd2 50. Rb6+ Kc8
Sample game 2 (1/2-1/2)
1. g4 g5 2. h4 h5 3. Qf3 f6 4. hxg5 fxg5 5. d4 Nb6 6. c3 Nc6 7. gxh5 Bxh5 8. Qg3 Bh6 9. Be4 O-O-O 10. d5 Nb8 11. Nc2 g4 12. Nd4 Rf8 13. Nf5 Bg5 14. Bd2 d6 15. Bxg5 Qxg5 16. Nd4 Qf6 17. Ne6 Rfg8 18. Qf4 N8d7 19. Nd3 Kb8 20. Bh1 Bf7 21. Qxf6 Nxf6 22. Ndf4 Nc4 23. b3 Bxe6 24. Nxe6 Ne5 25. c4 Rh2 26. Rc1 a5 27. Rc3 Rgh8 28. Bg2 c6 29. dxc6 bxc6 30. a3 R2h5 31. b4 a4 32. Nf4 R5h6 33. Nd3 Nfd7 34. Nb2 Rf8 35. Ke1 Nb6 36. c5 Nd5 37. Bxd5 cxd5 38. Nxa4 d4 39. Rcg3 d3 40. Nc3 dxc5 41. bxc5 Rc6 42. Ne4 Ra6 43. Kd2 Rxa3
Play it in the CH960 app
Open this page on a phone with the CH960 app installed, or find pair 88 / 266 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): nrknbbqr/pppppppp/8/8/8/8/PPPPPPPP/NBNRBKRQ w DGbh - 0 1
Mirror twin: White 877 vs Black 597 — a different position (castling squares are fixed), not evaluated by the search.
Current place in the live balance rating: 382.