White 242 vs Black 516

The two setups

White: setup #242 B N R K Q B N R

King on the d-file, rooks on c, h, queen on the e-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 242 gives White +0.17 (Morozov Balance Index, 400M nodes).

Black: setup #516 R B B N Q K N R

King on the f-file, rooks on a, h, queen on the e-file; no 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 516 gives White +0.21 (Morozov Balance Index, 400M nodes).

Why the pair is balanced

At the deepest rungs (400M, 800M, 1.6B nodes) the evaluation never left ±1 centipawns of equality, reaching search depth 59.

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 wandered between -8 and +41 cp before settling — a reminder that quick engine checks overstate imbalances, and why the ladder goes deep.

For comparison, in symmetric play setup 242 gives White +0.17 and setup 516 gives White +0.21: 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 e4, and 3 first moves are within 10 cp of it.

Along the engine's main line (23 moves) the evaluation stayed within ±17 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.

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.

This pair held exactly 0.00 up to 1 600 000 000 nodes.

Independent engines, run on the same position:

• Berserk 14: -2
• Lc0 0.32.1: +4

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 +43, Black +63, difference -20. 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.

Main-line play-out

23 moves, 5 000 000 nodes per half-move. Largest |evaluation| 17 cp, mean 4.0 cp, final 0 cp.

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 35.8 moves.

1. e4 c6 2. b3 d5 3. exd5 cxd5 4. Nf3 Qd7 5. Qe3 Nc6 6. Bb5 a6 7. Bxc6 bxc6 8. Be5 f6 9. Bxb8 Rxb8 10. d4 Nh6 11. O-O Nf5 12. Qd3 g5 13. Nc3 h5 14. Ne2 Kf7 15. Rfe1 Nd6 16. c4 h4 17. cxd5 cxd5 18. Nc3 Bb7 19. h3 g4 20. hxg4 Qxg4 21. Qe2 Qd7 22. Na4 Ne4 23. Nc5 Nxc5 24. Rxc5 Rbg8 25. Nh2 Bc8 26. Rc3 Qd6 27. Qc2 Bd7 28. Rce3 Re8 29. Nf3 Rh5 30. Qd1 Rhh8 31. Qc2 Bg4 32. Nh2 Bc8 33. Nf3 Bg4 34. Nh2 Bc8 35. Nf3

1. e4 c6 2. O-O-O a5 3. b3 d5 4. exd5 cxd5 5. a4 Nc6 6. Bb2 Bf5 7. Na3 Qc8 8. Kb1 Nf6 9. h3 Bd6 10. Rc1 O-O 11. g4 Bg6 12. Nf3 Ne4 13. d3 Bb4 14. c3 Bc5 15. Rc2 Nd6 16. Nh4 Bxa3 17. Bxa3 b5 18. Bxd6 exd6 19. axb5 Rb8 20. Nxg6 hxg6 21. d4 Na7 22. Qd2 Nxb5 23. Ka2 Rb7 24. Bxb5 Rxb5 25. Qd3 Rb6 26. f4 Re8 27. f5 Re4 28. Rf2 Rb8 29. fxg6 fxg6 30. Ka3 Qb7 31. Rb1 Qe7 32. Rf3 g5 33. Rh1 Rf4 34. Rhf1 Qb7 35. Qc2 Rbf8 36. Qd3 Qc7 37. Rxf4 gxf4 38. h4 Qe7 39. h5 Qe4 40. Qd2 f3

Play it in the CH960 app

Open this page on a phone with the CH960 app installed, or find pair 242 / 516 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): rbbnqknr/pppppppp/8/8/8/8/PPPPPPPP/BNRKQBNR w CHah - 0 1

Mirror twin (the same position mirrored): White 615 vs Black 542.

Current place in the live balance rating: 173.