White 75 vs Black 1
White starts from setup 75 (NNRKBQRB), Black from setup 1 (BQNBNRKR). In the encyclopedia since 2026-10-15: 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. 75, Black by position No. 1, 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 #75 N N R K B Q R B
King on the d-file, rooks on c, 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 75 gives White +0.38 (Morozov Balance Index, 400M nodes).
Black: setup #1 B Q N B N R K R
King on the g-file, rooks on f, h, queen on the b-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 1 gives White +0.19 (Morozov Balance Index, 400M nodes).
Why the pair is balanced
At the deepest rungs (400M, 800M, 1.6B nodes) the evaluation is exactly 0.00 each time, reaching search depth 59.
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 0 and +24 cp before settling — a reminder that quick engine checks overstate imbalances, and why the ladder goes deep.
For comparison, in symmetric play setup 75 gives White +0.38 and setup 1 gives White +0.19: 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 g4, and 2 first moves are within 10 cp of it.
Along the engine's main line (6 moves) the evaluation stayed within ±20 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 | +20 | 1. g3 b5 2. Bxa8 Qxa8 3. d3 c5 4. O-O-O h5 |
| S1 | 500 000 | 17 | +1 | 1. g3 f5 2. c4 Rf7 3. d3 O-O 4. Nb3 b6 |
| S2 | 2 000 000 | 21 | +3 | 1. g4 c5 2. e3 e6 3. d3 h5 4. g5 d5 |
| S3 | 8 000 000 | 27 | +24 | 1. g4 h5 2. g5 b5 3. Bxa8 Qxa8 4. O-O-O c5 |
| S4 | 32 000 000 | 35 | 0 | 1. g4 c5 2. e3 e6 3. Nb3 b6 4. Bxa8 Qxa8 |
| S5 | 128 000 000 | 40 | +6 | 1. g4 c5 2. e3 e6 3. Nb3 b6 4. Bxa8 Qxa8 |
| S6 | 400 000 000 | 50 | 0 | 1. g4 c5 2. O-O-O Bc7 3. h4 Bh2 4. Rg2 Be5 |
| S7 | 800 000 000 | 56 | 0 | 1. g4 c5 2. O-O-O Bc7 3. h4 Bh2 4. Rg2 Be5 |
| S8 | 1 600 000 000 | 59 | 0 | 1. g4 c5 2. O-O-O Bc7 3. h4 Bh2 4. Rg2 Be5 |
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: -8
- Lc0 0.32.1: -7
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 +80, Black +95, difference -15. 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 | 0 | 41 | 1. g4 c5 2. O-O-O Bc7 3. h4 Bh2 4. Rg2 Bd6 5. Rg1 |
| 2 | -10 | 40 | 1. g3 b5 2. Bxa8 Qxa8 3. Nb3 c6 4. d4 a5 5. O-O-O Qa7 |
| 3 | -14 | 40 | 1. O-O-O b5 2. Nb3 e6 3. g4 Bxh1 4. Rxh1 h5 5. h3 Be7 |
Main-line play-out
6 moves, 5 000 000 nodes per half-move. Largest |evaluation| 20 cp, mean 1.8 cp, final 0 cp.
| # | White | cp | Black | cp |
|---|---|---|---|---|
| 1 | g4 | +20 | c5 | +4 |
| 2 | O-O-O | 0 | Bc7 | 0 |
| 3 | h4 | 0 | Bh2 | 0 |
| 4 | Rg2 | 0 | Bd6 | 0 |
| 5 | Rg1 | 0 | Bh2 | 0 |
| 6 | Rg2 | 0 | Bd6 | 0 |
| 7 | Rg1 | 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 37.9 moves.
Sample game 1 (1/2-1/2)
1. g3 b5 2. d3 d5 3. Nb3 e6 4. e4 Be7 5. f4 dxe4 6. Bxe4 Nf6 7. Bxa8 Qxa8 8. N1d2 a5 9. Qf3 Qa6 10. Bf2 Rd8 11. Nc5 Bxc5 12. Bxc5 Nd6 13. O-O-O O-O 14. h4 b4 15. h5 Qb5 16. d4 Rfe8 17. g4 Qb7 18. Qe2 Nfe4 19. Rge1 Nxd2 20. Rxd2 Qd5 21. b3 Nb7 22. Red1 Nd6 23. Re1 Nb7 24. Red1 Nd6
Sample game 2 (1/2-1/2)
1. O-O-O b5 2. Nb3 f5 3. Nc5 Nf6 4. d4 Rf7 5. g4 Bxh1 6. Rxh1 fxg4 7. Nd3 e6 8. h3 g3 9. Ne5 Rf8 10. f3 d6 11. Nc6 Qb6 12. Nxd8 Rxd8 13. Bxg3 O-O 14. Bf2 Qa6 15. a3 Qc6 16. Qe1 Nb6 17. b3 Ra8 18. Qc3 Qb7 19. Qa5 Nbd5 20. Rh2 a6 21. Kb2 Nh5 22. Rg1 Kh8 23. Nc3 h6 24. Ne4 b4 25. axb4 Rf5 26. Nc5 dxc5 27. e4 Rxf3 28. exd5 Qxb4 29. Qxb4 cxb4 30. dxe6 a5 31. Ra1 Rf5 32. Be1 Re8 33. c4 bxc3+ 34. Bxc3 Nf4 35. Rxa5 Rxa5 36. Bxa5 c6 37. h4 Kg8 38. Kc3 Nxe6 39. Kc4 Rf8 40. Re2 Rf6 41. Re4
Play it in the CH960 app
Open this page on a phone with the CH960 app installed, or find pair 75 / 1 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): bqnbnrkr/pppppppp/8/8/8/8/PPPPPPPP/NNRKBQRB w CGfh - 0 1
Mirror twin: White 881 vs Black 955 — a different position (castling squares are fixed), not evaluated by the search.
Current place in the live balance rating: 329.