White 255 vs Black 134
White starts from setup 255 (NRKQNRBB), Black from setup 134 (NRBQNBKR). In the encyclopedia since 2026-10-03: neither side starts better.
|cp| ≤ 5 at 400M · 800M · 1.6B · 4B nodes, two independent engines agree
The two setups
White: setup #255 N R K Q N R B B
King on the c-file, rooks on b, f, queen on the d-file; one bishop starts in a corner; the knights start away from the centre. The king already stands on a castled square, so one of the castlings moves only the rook. In ordinary symmetric play setup 255 gives White +0.16 (Morozov Balance Index, 400M nodes).
Black: setup #134 N R B Q N B K R
King on the g-file, rooks on b, h, queen on the d-file; no bishop starts in a corner; the knights start away from the centre. The king already stands on a castled square, so one of the castlings moves only the rook. In ordinary symmetric play setup 134 gives White +0.22 (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 54.
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 shallow rungs agreed early: from 100 thousand to 128 million nodes the evaluation never left ±12 cp.
For comparison, in symmetric play setup 255 gives White +0.16 and setup 134 gives White +0.22: 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 f4; the alternatives are slightly weaker but keep the game level.
Along the engine's main line (30 moves) the evaluation stayed within ±30 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 | -3 | 1. f4 b6 2. g3 d5 3. Nf3 c5 4. Ne5 Bb7 |
| S1 | 500 000 | 21 | +3 | 1. f4 Nb6 2. g3 h5 3. Nf3 Rh6 4. Nb3 d6 |
| S2 | 2 000 000 | 24 | +12 | 1. f4 b6 2. e4 c5 3. Qe2 Nac7 4. O-O-O g6 |
| S3 | 8 000 000 | 31 | -11 | 1. f4 b6 2. e4 h5 3. Qe2 e6 4. O-O-O d5 |
| S4 | 32 000 000 | 33 | 0 | 1. f4 b6 2. e4 c5 3. c3 Nac7 4. Nac2 d5 |
| S5 | 128 000 000 | 46 | 0 | 1. f4 b6 2. e4 c5 3. Qe2 Nac7 4. O-O-O h5 |
| S6 | 400 000 000 | 53 | 0 | 1. f4 b6 2. e4 c5 3. Qe2 Nac7 4. O-O-O h5 |
| S7 | 800 000 000 | 53 | 0 | 1. f4 b6 2. e4 c5 3. Qe2 Nac7 4. O-O-O h5 |
| S8 | 1 600 000 000 | 54 | 0 | 1. f4 b6 2. e4 c5 3. Qe2 Nac7 4. O-O-O h5 |
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 | not checked |
| 8 000 000 000 | not checked |
| 16 000 000 000 | not checked |
This pair held exactly 0.00 up to 1 600 000 000 nodes.
Independent engines, run on the same position:
- Berserk 14: -6
- Lc0 0.32.1: -1
Independent confirmations: 2 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 +28, Black +15, difference +13. 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 | +1 | 40 | 1. f4 Nb6 2. e4 d6 3. Qe2 c5 4. c3 e5 5. g3 Be7 |
| 2 | -12 | 39 | 1. c3 Nf6 2. f4 Nb6 3. g3 d6 4. Nac2 c5 5. d4 Bh3 |
| 3 | -15 | 39 | 1. e4 c5 2. f4 d6 3. d4 cxd4 4. Bxd4 Nb6 5. Qe2 e5 |
Main-line play-out
30 moves, 5 000 000 nodes per half-move. Largest |evaluation| 30 cp, mean 8.6 cp, final 0 cp.
| # | White | cp | Black | cp |
|---|---|---|---|---|
| 1 | f4 | -9 | b6 | -9 |
| 2 | e4 | -16 | c5 | -1 |
| 3 | Qe2 | -9 | Nac7 | -4 |
| 4 | O-O-O | -8 | e6 | -13 |
| 5 | d3 | -9 | d5 | -4 |
| 6 | c3 | -5 | h5 | -6 |
| 7 | g3 | -8 | Nd6 | -7 |
| 8 | Nac2 | -10 | Qe8 | -8 |
| 9 | Kb1 | -21 | g6 | -17 |
| 10 | Bf2 | -21 | dxe4 | -27 |
| 11 | dxe4 | -22 | a5 | -30 |
| 12 | Nd3 | -20 | Ba6 | -25 |
| 13 | Rfe1 | -28 | a4 | -30 |
| 14 | Ka1 | -17 | Bg7 | -12 |
| 15 | e5 | -18 | Nc4 | -6 |
| 16 | Ne3 | -9 | Nxe3 | -10 |
| 17 | Bxe3 | -16 | Bc4 | -12 |
| 18 | Qc2 | -12 | Qb5 | -7 |
| 19 | Nf2 | -2 | Nd5 | -4 |
| 20 | Qc1 | -6 | f5 | -4 |
| 21 | exf6 | 0 | Bxf6 | -1 |
| 22 | Ne4 | 0 | O-O-O | -8 |
| 23 | Nxf6 | 0 | Nxf6 | 0 |
| 24 | Bg2 | 0 | Rxd1 | -5 |
| 25 | Rxd1 | 0 | Bd3 | 0 |
| 26 | Qd2 | 0 | Be2 | 0 |
| 27 | c4 | 0 | Qxc4 | 0 |
| 28 | Qd6 | 0 | Bxd1 | 0 |
| 29 | Qc6+ | 0 | Kd8 | 0 |
| 30 | Qd6+ | 0 | Kc8 | 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 34.1 moves.
Sample game 1 (1/2-1/2)
1. f4 b6 2. c3 Bb7 3. d3 d5 4. g3 Nd6 5. Qc2 c5 6. e4 h5 7. O-O-O Nc7 8. Nf3 a5 9. Rfe1 Rh6 10. f5 Qc8 11. Ne5 e6 12. Be3 Rh8 13. Kb1 exf5 14. exf5 d4 15. Bxb7 Qxb7 16. cxd4 Nxf5 17. dxc5 Nxe3 18. Rxe3 bxc5 19. d4 c4 20. Nxf7 Kxf7 21. Qxc4+ Nd5 22. Rf1+ Kg8 23. Rb3 Bb4 24. a3 Rc8 25. Qe2 Rh6 26. axb4 axb4 27. Nc2 Rhc6 28. Ne3 Re6 29. Qf3 Rf6 30. Qe2 Re6 31. Qf3 Rf6 32. Qe2
Sample game 2 (1/2-1/2)
1. e4 c5 2. g3 d6 3. f4 h5 4. e5 Bf5 5. Qe2 e6 6. Bg2 Nb6 7. h3 Nc7 8. Nb3 Ncd5 9. exd6 Bxd6 10. Bxc5 Rc8 11. Bxb6 Qxb6 12. g4 hxg4 13. hxg4 Bxc2 14. Nxc2 Rh2 15. O-O-O Nxf4 16. Rxf4 Qc7 17. Na1 Bxf4 18. Kb1 Bg5 19. a3 Qf4 20. Ne3 Qg3 21. Rg1 Bxe3 22. Qxe3 Qxe3 23. dxe3 Rd8 24. Kc1 Rc8+ 25. Kb1 Rd8 26. Kc1 Rc8+
Play it in the CH960 app
Open this page on a phone with the CH960 app installed, or find pair 255 / 134 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): nrbqnbkr/pppppppp/8/8/8/8/PPPPPPPP/NRKQNRBB w BFbh - 0 1
Mirror twin (the same position mirrored): White 608 vs Black 822.
Current place in the live balance rating: 177.