White 63 vs Black 609
White starts from setup 63 (NNRQKRBB), Black from setup 609 (BRNBQKRN). In the encyclopedia since 2026-10-03: 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. 63, Black by position No. 609, 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 #63 N N R Q K R B B
King on the e-file, rooks on c, f, queen on the d-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 63 gives White +0.23 (Morozov Balance Index, 400M nodes).
Black: setup #609 B R N B Q K R N
King on the f-file, rooks on b, g, queen on the e-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 609 gives White +0.28 (Morozov Balance Index, 400M nodes).
Why the pair is balanced
At the deepest rungs (400M, 800M, 1.6B, 3.2B nodes) the evaluation never left ±2 centipawns of equality, reaching search depth 62.
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 -20 and +18 cp before settling — a reminder that quick engine checks overstate imbalances, and why the ladder goes deep.
For comparison, in symmetric play setup 63 gives White +0.23 and setup 609 gives White +0.28: 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 (14 moves) the evaluation stayed within ±15 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 | 13 | -20 | 1. g3 e5 2. c4 O-O 3. Nc3 Ng6 4. h4 h5 |
| S1 | 500 000 | 20 | 0 | 1. g3 O-O 2. c4 b6 3. Bxa8 Rxa8 4. Qb3 e6 |
| S2 | 2 000 000 | 23 | +16 | 1. g3 e5 2. c4 b6 3. Bxa8 Rxa8 4. Qb3 O-O |
| S3 | 8 000 000 | 32 | +13 | 1. g3 e5 2. c4 O-O 3. Qb3 b6 4. Bxa8 Rxa8 |
| S4 | 32 000 000 | 37 | +18 | 1. g3 e5 2. c4 O-O 3. Qb3 b6 4. Bxa8 Rxa8 |
| S5 | 128 000 000 | 45 | +2 | 1. g3 e5 2. c4 O-O 3. Qb3 Ng6 4. Nc2 f5 |
| S6 | 400 000 000 | 51 | -2 | 1. g3 e5 2. c4 O-O 3. Qb3 Ng6 4. O-O-O b6 |
| S7 | 800 000 000 | 54 | +1 | 1. g3 e5 2. c4 O-O 3. Qb3 Ng6 4. Nc2 f5 |
| S8 | 1 600 000 000 | 57 | 0 | 1. g3 e5 2. c4 O-O 3. Qb3 Ng6 4. Nc3 f5 |
| S9 | 3 200 000 000 | 62 | 0 | 1. g3 e5 2. c4 O-O 3. Qb3 Ng6 4. Nc3 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 | 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 +30, Black +137, difference -107. 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 | +4 | 41 | 1. g3 e5 2. c4 O-O 3. Qb3 b6 4. Bxa8 Rxa8 5. Nc2 f5 |
| 2 | -58 | 41 | 1. e4 e5 2. g3 O-O 3. Qh5 b5 4. d3 g6 5. Qh3 f5 |
| 3 | -80 | 40 | 1. c4 b6 2. Nc3 e5 3. f3 O-O 4. g3 f5 5. Qb3 Ne7 |
Main-line play-out
14 moves, 5 000 000 nodes per half-move. Largest |evaluation| 15 cp, mean 3.2 cp, final 0 cp.
| # | White | cp | Black | cp |
|---|---|---|---|---|
| 1 | g3 | +15 | e5 | +12 |
| 2 | c4 | +13 | O-O | +12 |
| 3 | Qb3 | +7 | b6 | +10 |
| 4 | Bxa8 | +7 | Rxa8 | 0 |
| 5 | O-O-O | +8 | f5 | 0 |
| 6 | Nc3 | 0 | Ng6 | 0 |
| 7 | Kb1 | 0 | Qf7 | 0 |
| 8 | f4 | 0 | exf4 | 0 |
| 9 | gxf4 | 0 | c6 | +4 |
| 10 | d3 | +3 | Nd6 | 0 |
| 11 | Nc2 | +1 | Bf6 | 0 |
| 12 | Bd4 | 0 | Be7 | 0 |
| 13 | Bg1 | 0 | Bf6 | 0 |
| 14 | Bd4 | 0 | Be7 | 0 |
| 15 | Bg1 | 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 48.8 moves.
Sample game 1 (1/2-1/2)
1. g3 b5 2. Bxa8 Rxa8 3. e4 O-O 4. Qe2 c6 5. O-O-O f6 6. f4 e5 7. Nb3 a5 8. fxe5 fxe5 9. a4 bxa4 10. Rxf8+ Qxf8 11. Qc4+ Qf7 12. Qxa4 Nb6 13. Bxb6 Bxb6 14. Na3 Qf2 15. Nc4 Nf7 16. Nxb6 Qxb6 17. Qc4 Qb4 18. d3 Kf8 19. Qc5+ Qxc5 20. Nxc5 Ke7 21. b3 Rb8 22. Kd2 d6 23. Na4 Nd8 24. Nc3 Ne6 25. h4 Nd4 26. Ne2 Nf3+ 27. Kc3 d5 28. exd5 cxd5 29. d4 Nxd4 30. Nxd4 exd4+ 31. Rxd4 Rc8+ 32. Kd3 Ke6 33. Ra4 Rc5 34. c3 g6 35. Kd4 Kd6 36. g4 Kc6 37. g5 Rb5 38. Ra2 Kb6 39. Ra3 Kb7 40. Ra1 Kb6
Sample game 2 (1/2-1/2)
1. g3 e6 2. c4 b6 3. Bxa8 Rxa8 4. e4 d5 5. Qe2 dxe4 6. Qxe4 Rb8 7. Nc3 O-O 8. Qe2 Nd6 9. Nc2 Bf6 10. b3 c5 11. O-O-O b5 12. f4 bxc4 13. Bxc5 Qc6 14. Bxd6 Qxd6 15. Qxc4 Rfc8 16. Ne4 Qd8 17. Qe2 Qa5 18. Kb1 Rxc2 19. Kxc2 Qxa2+ 20. Kd3 Qxb3+ 21. Nc3 Bxc3 22. dxc3 Ng6 23. Ke3 Qxc3+ 24. Qd3 Qc5+ 25. Kf3 Qc6+ 26. Kf2 h5 27. Rb1 Rc8 28. Qb5 Qe4 29. Rbc1 Qd4+ 30. Ke2 Qe4+ 31. Kf2 Qd4+ 32. Kf3 Rxc1 33. Rxc1 Ne7 34. Re1 Nf5 35. Qe8+ Kh7 36. Qxf7 Qd5+ 37. Kf2 Nd4 38. f5 Qf3+ 39. Kg1 Ne2+ 40. Rxe2 Qxe2
Play it in the CH960 app
Open this page on a phone with the CH960 app installed, or find pair 63 / 609 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): brnbqkrn/pppppppp/8/8/8/8/PPPPPPPP/NNRQKRBB w CFbg - 0 1
Mirror twin: White 896 vs Black 251 — a different position (castling squares are fixed), not evaluated by the search.
Current place in the live balance rating: 17.