White 129 vs Black 918
White starts from setup 129 (BNRBQNKR), Black from setup 918 (RKBRQBNN). 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 #129 B N R B Q N K R
King on the g-file, rooks on c, h, queen on the e-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 129 gives White +0.35 (Morozov Balance Index, 400M nodes).
Black: setup #918 R K B R Q B N N
King on the b-file, rooks on a, d, queen on the e-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 918 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 ±4 centipawns of equality, reaching search depth 53.
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 ±9 cp.
For comparison, in symmetric play setup 129 gives White +0.35 and setup 918 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 e4; the alternatives are slightly weaker but keep the game level.
Along the engine's main line (13 moves) the evaluation stayed within ±23 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 1, drawn 9, Black won 0 (White scored 55.0%).
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 | 17 | -9 | 1. c4 e5 2. Ng3 Nf6 3. Nc3 Ng6 4. e3 d5 |
| S1 | 500 000 | 20 | -4 | 1. c4 e5 2. b3 f5 3. d4 exd4 4. Bxd4 Ne7 |
| S2 | 2 000 000 | 22 | +4 | 1. c4 e5 2. b3 f5 3. Bc2 d6 4. e3 Nf6 |
| S3 | 8 000 000 | 30 | 0 | 1. c4 e5 2. b3 f5 3. d4 exd4 4. Bxd4 Ng6 |
| S4 | 32 000 000 | 36 | 0 | 1. c4 e5 2. b3 f5 3. d4 d6 4. e4 Ng6 |
| S5 | 128 000 000 | 38 | -4 | 1. c4 e5 2. b3 Ng6 3. e3 f5 4. d4 d5 |
| S6 | 400 000 000 | 44 | +4 | 1. c4 e5 2. b3 f5 3. Ne3 f4 4. Nd5 c6 |
| S7 | 800 000 000 | 48 | 0 | 1. c4 e5 2. b3 Ng6 3. Nc3 a5 4. e3 Nf6 |
| S8 | 1 600 000 000 | 53 | 0 | 1. c4 e5 2. b3 Ng6 3. Nc3 a5 4. e3 f5 |
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: +1
- 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 +82, Black +132, difference -50. A balanced pair needs White's setup to be weaker by about the price of the first move.
Extended self-play: 10 games, 1 White wins, 9 draws, 0 Black wins, White scored 55.0%.
Best first moves
The 3 best first moves for White, searched together at 400 000 000 nodes.
| # | Eval, cp | Depth | Main line |
|---|---|---|---|
| 1 | -10 | 40 | 1. e4 e6 2. b3 Ne7 3. Ne3 d5 4. exd5 exd5 5. d4 a5 |
| 2 | -26 | 39 | 1. c4 e5 2. b3 a5 3. Ng3 Nf6 4. O-O d5 5. e3 d4 |
| 3 | -26 | 39 | 1. b3 d5 2. c4 dxc4 3. bxc4 e5 4. e3 a5 5. Ng3 Ng6 |
Main-line play-out
13 moves, 5 000 000 nodes per half-move. Largest |evaluation| 23 cp, mean 3.4 cp, final 0 cp.
| # | White | cp | Black | cp |
|---|---|---|---|---|
| 1 | c4 | -6 | e5 | -15 |
| 2 | Ng3 | -22 | Ng6 | -23 |
| 3 | e3 | -8 | Nf6 | -16 |
| 4 | Nc3 | -3 | a5 | 0 |
| 5 | Qe2 | 0 | d5 | 0 |
| 6 | cxd5 | 0 | Nxd5 | 0 |
| 7 | Nxd5 | 0 | Rxd5 | 0 |
| 8 | Bb3 | 0 | Rd8 | 0 |
| 9 | Qc4 | 0 | Rd7 | 0 |
| 10 | O-O | 0 | Qd8 | 0 |
| 11 | Ba4 | 0 | Rd5 | 0 |
| 12 | Bb3 | 0 | Rd7 | 0 |
| 13 | Ba4 | 0 | Rd5 | 0 |
| 14 | Bb3 | 0 |
Engine self-play
10 games at 500 000 nodes per move: White won 1, drawn 9, Black won 0 — White scored 55.0%. Average length 45.4 moves.
Sample game 1 (1/2-1/2)
1. c4 a5 2. b3 f5 3. Ne3 e6 4. O-O d5 5. Nc2 e5 6. d4 Nf7 7. e3 Nf6 8. Nc3 e4 9. f4 exf3 10. Bxf3 Ng5 11. Bxd5 Ra6 12. Bf3 Nfe4 13. Bxe4 fxe4 14. Nb5 Qh5 15. d5 Nf3+ 16. gxf3 Rg6+ 17. Kh1 Bh3 18. Rf2 exf3 19. Qxa5 Bd6 20. Qa7+ Kc8 21. Nxd6+ Rdxd6 22. Qa8+ Kd7 23. Qa4+ Ke7 24. Qa5 Kd7 25. Qa4+ Ke7 26. Qa5 b6 27. Qa7 Kd7 28. Qa4+ Kd8 29. Qa8+ Ke7 30. Qa7 Bg2+ 31. Rxg2 fxg2+ 32. Kg1 Kd7 33. Qa4+ Kd8 34. Qa8+ Kd7 35. Qa4+ Ke7 36. Qa7 Rd7 37. Qb7 Rh6 38. d6+ Rhxd6 39. Nd4 Kf7 40. Nf3 c6 41. Ne5+ Ke7 42. Nxd7 Rd1+ 43. Rxd1 Qxd1+ 44. Kxg2 Qe2+ 45. Kg3 Qxe3+ 46. Kg2
Sample game 2 (1/2-1/2)
1. e3 d5 2. c4 dxc4 3. Qe2 e5 4. Qxc4 Bd6 5. Ng3 a5 6. Ne4 Qe7 7. O-O Ng6 8. Nxd6 Rxd6 9. Be2 Nf6 10. b3 b6 11. Qc2 Bb7 12. Na3 O-O-O 13. Nc4 Rc6 14. f4 exf4 15. Bf3 Nd5 16. Qf5+ Qe6 17. Qxe6+ fxe6 18. Be4 e5 19. h4 Nxh4 20. Bxe5 g5 21. exf4 gxf4 22. Bxf4 Nxf4 23. Rxf4 Rh6 24. d3 Bxe4 25. dxe4 Ng6 26. Rf6 Kb8 27. Ne5 Rd6 28. Rxd6 cxd6 29. Nc6+ Kb7 30. Nd4 Nf4 31. Rd1 Rf6 32. Rf1 b5 33. Rf3 Kb6 34. Kf2 Nd3+ 35. Ke3 Rxf3+ 36. gxf3 Ne5 37. f4 Ng4+ 38. Kf3 h5 39. a3 b4 40. axb4 axb4 41. Kg3 Nf6 42. e5 dxe5 43. fxe5 Ne8 44. Nc2
Play it in the CH960 app
Open this page on a phone with the CH960 app installed, or find pair 129 / 918 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): rkbrqbnn/pppppppp/8/8/8/8/PPPPPPPP/BNRBQNKR w CHad - 0 1
Mirror twin (the same position mirrored): White 827 vs Black 38.