White 107 vs Black 291
White starts from setup 107 (QNRNBKRB), Black from setup 291 (BQNRKRNB). 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. 107, Black by position No. 291, 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 #107 Q N R N B K R B
King on the f-file, rooks on c, g, queen on the a-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 107 gives White +0.31 (Morozov Balance Index, 400M nodes).
Black: setup #291 B Q N R K R N B
King on the e-file, rooks on d, f, queen on the b-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 291 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 never left ±5 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 same corridor is required at every deeper budget (8 G, 16 G) at which the pair has been evaluated.
The shallow rungs agreed early: from 100 thousand to 128 million nodes the evaluation never left ±12 cp.
For comparison, in symmetric play setup 107 gives White +0.31 and setup 291 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 g3, and 2 first moves are within 10 cp of it.
Along the engine's main line (30 moves) the evaluation stayed within ±16 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 | -9 | 1. c4 b6 2. d3 g6 3. O-O f5 4. g3 Bxh1 |
| S1 | 500 000 | 21 | -3 | 1. c4 b6 2. d3 c5 3. g3 Bxh1 4. Rxh1 Nf6 |
| S2 | 2 000 000 | 25 | -12 | 1. g3 d5 2. b4 b6 3. d3 Nf6 4. Bc3 O-O |
| S3 | 8 000 000 | 30 | +5 | 1. g3 b6 2. Bxa8 Qxa8 3. c4 g5 4. d3 f5 |
| S4 | 32 000 000 | 37 | +8 | 1. g3 d5 2. b4 Nh6 3. d3 g6 4. Bc3 d4 |
| S5 | 128 000 000 | 42 | +3 | 1. c4 b6 2. d3 Nf6 3. Ne3 c5 4. O-O O-O |
| S6 | 400 000 000 | 49 | 0 | 1. g3 b6 2. Bxa8 Qxa8 3. c4 Qc6 4. d3 Qh6 |
| S7 | 800 000 000 | 49 | -5 | 1. g3 b6 2. Bxa8 Qxa8 3. c4 Nf6 4. d3 d5 |
| S8 | 1 600 000 000 | 56 | 0 | 1. g3 b6 2. Bxa8 Qxa8 3. c4 Nf6 4. d3 d5 |
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: -2
- Lc0 0.32.1: +15
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 +26, Black +67, difference -41. 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 | 46 | 1. g3 b6 2. Bxa8 Qxa8 3. c4 Nf6 4. d3 d5 5. cxd5 Nxd5 |
| 2 | -10 | 46 | 1. d3 b6 2. c4 g5 3. Bc3 Bxc3 4. Nbxc3 e6 5. O-O f5 |
| 3 | -12 | 46 | 1. c4 b6 2. d3 g5 3. Bc3 Bxc3 4. Nbxc3 e6 5. O-O f5 |
Main-line play-out
30 moves, 5 000 000 nodes per half-move. Largest |evaluation| 16 cp, mean 3.0 cp, final 0 cp.
| # | White | cp | Black | cp |
|---|---|---|---|---|
| 1 | g3 | -5 | d5 | +7 |
| 2 | b4 | +14 | Nh6 | +10 |
| 3 | d3 | +11 | g6 | +16 |
| 4 | Bc3 | +15 | d4 | +11 |
| 5 | Bb2 | +11 | b6 | +8 |
| 6 | Bxa8 | +9 | Qxa8 | +4 |
| 7 | b5 | +4 | a6 | 0 |
| 8 | c3 | 0 | Nf5 | 0 |
| 9 | g4 | 0 | dxc3 | 0 |
| 10 | Nbxc3 | 0 | Nd4 | -6 |
| 11 | Ne4 | -8 | Qd5 | 0 |
| 12 | Rxc7 | 0 | f5 | 0 |
| 13 | Ne3 | 0 | Qe5 | 0 |
| 14 | Qc1 | 0 | fxe4 | 0 |
| 15 | Bxd4 | 0 | Qxd4 | 0 |
| 16 | Rxc8 | 0 | exd3 | 0 |
| 17 | Qc6+ | 0 | Kf7 | 0 |
| 18 | Rxd8 | +3 | dxe2+ | 0 |
| 19 | Kxe2 | +10 | Rxd8 | +2 |
| 20 | Qc2 | 0 | Qe5 | +1 |
| 21 | bxa6 | 0 | Qb5+ | 0 |
| 22 | Qc4+ | 0 | Qxc4+ | 0 |
| 23 | Nxc4 | +5 | Ra8 | -1 |
| 24 | Rg3 | +4 | b5 | +3 |
| 25 | Rf3+ | +6 | Kg8 | 0 |
| 26 | Nd2 | 0 | Rxa6 | 0 |
| 27 | a3 | -3 | Ra5 | 0 |
| 28 | h3 | 0 | Bf6 | 0 |
| 29 | Nb1 | 0 | h6 | 0 |
| 30 | Rb3 | 0 | Kf7 | 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 31.6 moves.
Sample game 1 (1/2-1/2)
1. g3 b6 2. Bxa8 Qxa8 3. c4 Nf6 4. d3 d5 5. cxd5 Nxd5 6. Nbc3 c5 7. Nxd5 Qxd5 8. Ne3 Qe6 9. b4 g6 10. Qb1 cxb4 11. Bxb4 Qh3+ 12. Ng2 Qxh2 13. Rc4 Bf6 14. Bc3 Nd6 15. Bxf6 Nxc4 16. Qb5+ Rd7 17. Qxc4 exf6 18. Qe4+ Kd8 19. Qa8+ Ke7 20. Qe4+ Kd8 21. Qa8+ Ke7 22. Qe4+
Sample game 2 (1/2-1/2)
1. g3 b6 2. Bxa8 Qxa8 3. c4 Nf6 4. d3 d5 5. cxd5 Nxd5 6. Nbc3 c5 7. Nxd5 Qxd5 8. Ne3 Qe6 9. b4 g6 10. Qb1 cxb4 11. Bxb4 Qh3+ 12. Ng2 Qxh2 13. Rc4 Bf6 14. Bc3 Nd6 15. Bxf6 Nxc4 16. Qb5+ Rd7 17. Qxc4 exf6 18. Qe4+ Kd8 19. Qa8+ Ke7 20. Qe4+ Kd8 21. Qa8+ Ke7 22. Qe4+
Play it in the CH960 app
Open this page on a phone with the CH960 app installed, or find pair 107 / 291 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): bqnrkrnb/pppppppp/8/8/8/8/PPPPPPPP/QNRNBKRB w CGdf - 0 1
Mirror twin: White 849 vs Black 371 — a different position (castling squares are fixed), not evaluated by the search.
Current place in the live balance rating: 432.