White 6 vs Black 99
White starts from setup 6 (QNBNRBKR), Black from setup 99 (BQNRNKRB). 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. 6, Black by position No. 99, 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 #6 Q N B N R B K R
King on the g-file, rooks on e, h, queen on the a-file; no 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 6 gives White +0.26 (Morozov Balance Index, 400M nodes).
Black: setup #99 B Q N R N K R B
King on the f-file, rooks on d, g, 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 99 gives White +0.17 (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 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 +26 cp before settling — a reminder that quick engine checks overstate imbalances, and why the ladder goes deep.
For comparison, in symmetric play setup 6 gives White +0.26 and setup 99 gives White +0.17: 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 b4, and 3 first moves are within 10 cp of it.
Along the engine's main line (15 moves) the evaluation stayed within ±11 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 | 14 | +26 | 1. h4 c5 2. e4 b6 3. d3 Nf6 4. Nbc3 d5 |
| S1 | 500 000 | 20 | +1 | 1. h4 c5 2. e4 g6 3. d3 b6 4. Rh3 Bg7 |
| S2 | 2 000 000 | 23 | -4 | 1. d4 d5 2. h4 g6 3. Bh6+ Bg7 4. Bxg7+ Nxg7 |
| S3 | 8 000 000 | 27 | -16 | 1. e4 g6 2. h4 c5 3. d3 b6 4. h5 d5 |
| S4 | 32 000 000 | 35 | -12 | 1. e4 g6 2. h4 b6 3. d3 d5 4. Nd2 c5 |
| S5 | 128 000 000 | 40 | -10 | 1. e4 g6 2. h4 d5 3. d3 b6 4. exd5 Bxd5 |
| S6 | 400 000 000 | 48 | 0 | 1. b4 g6 2. Bb2 Bxb2 3. Qxb2 d5 4. d4 b6 |
| S7 | 800 000 000 | 50 | +4 | 1. b4 g6 2. Bb2 Bxb2 3. Qxb2 d5 4. d4 b6 |
| S8 | 1 600 000 000 | 57 | 0 | 1. b4 d5 2. Bb2 b6 3. d3 c5 4. bxc5 bxc5 |
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: +4
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 +89, Black +129, difference -40. 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 | 45 | 1. b4 g6 2. Bb2 Bxb2 3. Qxb2 d5 4. d4 b6 5. e3 Ncd6 |
| 2 | 0 | 45 | 1. e4 g6 2. h4 c5 3. h5 g5 4. Ne3 b6 5. d3 d5 |
| 3 | -1 | 45 | 1. h4 d5 |
Main-line play-out
15 moves, 5 000 000 nodes per half-move. Largest |evaluation| 11 cp, mean 0.7 cp, final 0 cp.
| # | White | cp | Black | cp |
|---|---|---|---|---|
| 1 | e4 | -10 | g6 | -11 |
| 2 | h4 | -2 | b6 | 0 |
| 3 | d3 | 0 | c5 | 0 |
| 4 | h5 | 0 | g5 | 0 |
| 5 | Ne3 | 0 | d5 | 0 |
| 6 | exd5 | 0 | Bxd5 | 0 |
| 7 | Nf5 | 0 | Be5 | 0 |
| 8 | Nh6 | 0 | Rg7 | 0 |
| 9 | Nf5 | 0 | Rg8 | 0 |
| 10 | Nh6 | 0 | Rg7 | 0 |
| 11 | Nf5 | 0 | Rg8 | 0 |
| 12 | Nd2 | 0 | Nf6 | 0 |
| 13 | Nh6 | 0 | Rg7 | 0 |
| 14 | Nf5 | 0 | Rg8 | 0 |
| 15 | Nh6 | 0 | Rg7 | 0 |
| 16 | Nf5 | 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 31.4 moves.
Sample game 1 (1/2-1/2)
1. h4 d5 2. Rh3 b6 3. d3 c5 4. e4 g6 5. Nbc3 d4 6. Ne2 h5 7. c3 Bg7 8. cxd4 cxd4 9. f4 e6 10. b4 b5 11. e5 Ne7 12. Nxd4 Nc7 13. Nb3 Ncd5 14. Bd2 Nf5 15. Nf2 Bh6 16. Qc1 a5 17. a3 axb4 18. axb4 Rd7 19. g4 hxg4 20. Nxg4 Ra7 21. Re2 Ra2 22. Nxh6 Nxh6 23. Be3 Rxe2 24. Bc5+ Kg7 25. Bxe2 Nf5 26. Bg4 Qb7 27. Bxf5 gxf5 28. Rg3+ Kh8 29. Rxg8+ Kxg8 30. Kf2 Kh7 31. Nd4 Nxb4 32. Bxb4 Qg2+ 33. Ke3 Qg3+ 34. Ke2 Qh2+ 35. Ke3 Qg3+ 36. Ke2 Qg2+ 37. Ke3
Sample game 2 (1/2-1/2)
1. h4 c5 2. b4 b6 3. bxc5 bxc5 4. e4 g6 5. Bb2 Bxb2 6. Qxb2 Ncd6 7. Qxb8 Rxb8 8. Nbc3 e6 9. f3 f5 10. e5 Nf7 11. Na4 Rb1 12. Nxc5 Nxe5 13. f4 Ng4 14. Nxd7+ Ke7 15. Nc5 Ng7 16. Rh3 Rd8 17. Rd3 Rd6 18. Be2 Nh5 19. Ra3 a6 20. Nd3 Be4 21. Nc3 Rxe1+ 22. Nxe1 Rxd2 23. Bxg4 fxg4 24. Nxe4 Re2 25. Ng3 Nxg3 26. Rxg3 Rxe1+ 27. Kf2 Rc1 28. Rxg4 Rxc2+ 29. Kf3 Rxa2 30. Rg5 Ra3+ 31. Ke4 Ra4+ 32. Kf3 Ra3+ 33. Ke4 Ra4+ 34. Ke3 Ra3+
Play it in the CH960 app
Open this page on a phone with the CH960 app installed, or find pair 6 / 99 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): bqnrnkrb/pppppppp/8/8/8/8/PPPPPPPP/QNBNRBKR w EHdg - 0 1
Mirror twin: White 950 vs Black 851 — a different position (castling squares are fixed), not evaluated by the search.
Current place in the live balance rating: 82.