White 35 vs Black 401
White starts from setup 35 (BNNQRKRB), Black from setup 401 (BRQBNNKR). 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. 35, Black by position No. 401, 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 #35 B N N Q R K R B
King on the f-file, rooks on e, g, queen on the d-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 35 gives White +0.06 (Morozov Balance Index, 400M nodes).
Black: setup #401 B R Q B N N K R
King on the g-file, rooks on b, h, queen on the c-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 401 gives White -0.07 (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 60.
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 -29 and +13 cp before settling — a reminder that quick engine checks overstate imbalances, and why the ladder goes deep.
For comparison, in symmetric play setup 35 gives White +0.06 and setup 401 gives White -0.07: 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 g3; the alternatives are slightly weaker but keep the game level.
Along the engine's main line (30 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 9, Black won 1 (White scored 45.0%).
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 | -29 | 1. g3 c5 2. b3 h5 3. h4 Rh6 4. e3 b5 |
| S1 | 500 000 | 21 | -4 | 1. g3 c5 2. b3 h5 3. h4 d6 4. c4 b5 |
| S2 | 2 000 000 | 25 | +13 | 1. g3 c5 2. b3 h5 3. c4 b5 4. Bxa8 Rxa8 |
| S3 | 8 000 000 | 31 | 0 | 1. g3 c5 2. b3 h5 3. c4 b5 4. Bxa8 Rxa8 |
| S4 | 32 000 000 | 35 | +2 | 1. g3 h5 2. b3 d6 3. Nd3 Rh6 4. e3 b5 |
| S5 | 128 000 000 | 40 | +8 | 1. g3 h5 2. b3 d6 3. Nd3 b5 4. Bxa8 Rxa8 |
| S6 | 400 000 000 | 50 | 0 | 1. g3 h5 2. b3 b5 3. Bxa8 Rxa8 4. e4 d6 |
| S7 | 800 000 000 | 55 | 0 | 1. g3 h5 2. b3 b5 3. Bxa8 Rxa8 4. e4 d6 |
| S8 | 1 600 000 000 | 60 | 0 | 1. g3 h5 2. b3 b5 3. Bxa8 Rxa8 4. e4 d6 |
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: -10
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 +81, Black +119, difference -38. 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, 9 draws, 1 Black wins, White scored 45.0%.
Best first moves
The 3 best first moves for White, searched together at 400 000 000 nodes.
| # | Eval, cp | Depth | Main line |
|---|---|---|---|
| 1 | 0 | 39 | 1. g3 h5 2. b3 b5 3. Bxa8 Rxa8 4. e4 d6 5. f4 c6 |
| 2 | -13 | 38 | 1. a4 h5 2. b3 h4 3. g4 hxg3 4. hxg3 b5 5. Bxa8 Rxa8 |
| 3 | -29 | 38 | 1. b3 b5 2. g3 Bxh1 3. Rxh1 d5 4. d4 Qh3+ 5. Kg1 c6 |
Main-line play-out
30 moves, 5 000 000 nodes per half-move. Largest |evaluation| 20 cp, mean 5.5 cp, final 0 cp.
| # | White | cp | Black | cp |
|---|---|---|---|---|
| 1 | g3 | 0 | h5 | +16 |
| 2 | b3 | -1 | Rh6 | +6 |
| 3 | d4 | +19 | b5 | +12 |
| 4 | Bxa8 | +8 | Rxa8 | -2 |
| 5 | Nd3 | 0 | d6 | 0 |
| 6 | c4 | +2 | c6 | +1 |
| 7 | Nd2 | 0 | bxc4 | +3 |
| 8 | bxc4 | +3 | d5 | +9 |
| 9 | Qc2 | +13 | Rb8 | +5 |
| 10 | f3 | +2 | Bc7 | 0 |
| 11 | Kg2 | 0 | h4 | 0 |
| 12 | g4 | 0 | Ng6 | +5 |
| 13 | Kh1 | 0 | h3 | -9 |
| 14 | Ne5 | -8 | Qe6 | -7 |
| 15 | e4 | -20 | Ba5 | -19 |
| 16 | Nxg6 | -17 | Qxg6 | -9 |
| 17 | Bc3 | -7 | Bc7 | -14 |
| 18 | Nf1 | -14 | e6 | -16 |
| 19 | Qe2 | -11 | Bf4 | -9 |
| 20 | Ng3 | -13 | Nf6 | -14 |
| 21 | e5 | -10 | Nd7 | -6 |
| 22 | Rd1 | -10 | Nb6 | -10 |
| 23 | Rb1 | 0 | dxc4 | 0 |
| 24 | Ne4 | 0 | Rd8 | 0 |
| 25 | a4 | -1 | Nxa4 | 0 |
| 26 | Qxc4 | 0 | Nxc3 | 0 |
| 27 | Qxc3 | 0 | Rh8 | 0 |
| 28 | g5 | 0 | Qf5 | 0 |
| 29 | Nd6 | 0 | Rxd6 | 0 |
| 30 | exd6 | 0 | Bxd6 | 0 |
Engine self-play
10 games at 500 000 nodes per move: White won 0, drawn 9, Black won 1 — White scored 45.0%. Average length 45.9 moves.
Sample game 1 (1/2-1/2)
1. O-O h5 2. e3 d5 3. g3 b5 4. b4 a5 5. a3 c5 6. bxc5 Qxc5 7. Be5 Bc7 8. Nd3 Qc4 9. Nc3 Nd7 10. f4 Nef6 11. Qe2 Ne4 12. Bd4 h4 13. g4 h3 14. Bf3 f6 15. g5 Rh4 16. Bg4 Nf8 17. gxf6 exf6 18. Nxe4 dxe4 19. Nf2 Qf7 20. Bf5 Re8 21. Qxb5 Rh5 22. Nh1 g6 23. Ng3 gxf5 24. Kf2 Rb8 25. Qa6 Rh7 26. Rg1 Qe6 27. Qa7 Rc8 28. Nh5+ Kf7 29. Nxf6 Rh6 30. Nh5 Rg6 31. Rxg6 Qxg6 32. Rg1 Qxh5 33. Rg7+ Ke8 34. Qc5 Qf3+ 35. Ke1 Qh1+ 36. Kf2 Qxh2+ 37. Kf1 Qh1+ 38. Kf2 Qf3+ 39. Ke1 Qh1+ 40. Kf2 Qf3+
Sample game 2 (1/2-1/2)
1. O-O h5 2. b3 h4 3. g4 hxg3 4. fxg3 d6 5. Bg2 b5 6. Bxa8 Rxa8 7. e3 e5 8. Qf3 Nf6 9. Nc3 c6 10. Ne4 Qh3 11. Nxf6+ Bxf6 12. Re2 e4 13. Qxe4 Bxa1 14. c3 Qd7 15. Ref2 Bxc3 16. dxc3 Re8 17. Qf5 Re7 18. Ne2 Qe8 19. Qg4 Ne6 20. Rf6 d5 21. Nd4 Nxd4 22. exd4 Re4 23. Qg5 O-O 24. h4 Re1 25. Rf2 a5 26. Qf5 Re3 27. Rf3 a4 28. h5 Rxf3 29. Rxf3 Qe2 30. Rf4 Qe7 31. h6 Re8 32. hxg7 Kxg7 33. Rg4+ Kf8 34. Rf4 Qe1+ 35. Kg2 Qe2+ 36. Kg1 Qe1+ 37. Kg2 Qe2+ 38. Kg1
Play it in the CH960 app
Open this page on a phone with the CH960 app installed, or find pair 35 / 401 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): brqbnnkr/pppppppp/8/8/8/8/PPPPPPPP/BNNQRKRB w EGbh - 0 1
Mirror twin: White 915 vs Black 747 — a different position (castling squares are fixed), not evaluated by the search.
Current place in the live balance rating: 176.