Starting position #259
Back-rank setup: BNRKNQRB
SP-259 · ThroneGuard — A central king (d or e) and two knights tucked onto inner files: the family that holds the standard array, SP-518.
Move the pieces right on the board — full Chess960 rules, castle by dropping the king on the rook.
Position features
The king starts on d1, the rooks on c1 and g1, the queen on f1.
Castling long simply swaps the two pieces: the king on d1 and the rook on c1 trade places.
A bishop starts in the corner on a1: it has a single diagonal, which the b-pawn unlocks, running out to h8.
The second rank carries 2 pawns with no defender at all: a2, h2.
The setup belongs to the ThroneGuard family; read right to left it becomes position 595.
The engine's main line opens with b3.
Every sentence here is computed from the setup itself and can be checked on the board.
Balance
MBI 98 Morozov Balance Index: 98 of 100 — class A — most balanced.
- Engine evaluation of the starting position: +3 centipawns for White (depth 45, 400 000 000 nodes).
- Rank 21 of 960 by balance — 1 is the most balanced start.
- In 50 self-play games White scored 47.0% (95% CI 33.9–60.6%).
- Balance band E — even · dynamics along the play-out: stable
- Evaluation along the engine's main line (70 half-moves): +35 → +28 → +15 → 0
- Deeper check (1 200 000 000 nodes, depth 47): +8 cp, +5 cp against the base run — verified
Position facts
- Mirror twin: position #595
- The king starts on d, the rooks on c and g
- King and rook are neighbours — castling from adjacent squares feels unusual
- It becomes the daily position in 418 days
Puzzles from this position
- Attack on the uncastled king: pawn to f6 (g5·7) — Chess960 specifics · 780
- Winning blow: knight to f6 (e4·2) — Chess960 specifics · 920
- Winning blow: rook to c7 (d7·2) — Chess960 specifics · 1010
- Winning blow: knight to c6 (b4·6) — Chess960 specifics · 1200
- Winning blow: queen to c7 (h7·2) — Chess960 specifics · 1200
- Winning blow: queen to d7 (c7) — Chess960 specifics · 1290
- Winning blow: knight to e4 (c3·8) — Chess960 specifics · 1480
- Mate in 3: queen to e7 (h4·4) — Chess960 specifics · 1630
- Winning blow: rook to b7 (b8·4) — Chess960 specifics · 1870
- Winning blow: queen to b7 (a7·8) — Chess960 specifics · 1930
This position appears in course day 123
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Commentary
The engine puts this start at +3 centipawns — about as close to level as a game of chess begins. Both corners hold a bishop, a1 towards h8 and h1 towards a8, each with a single diagonal. The line shows why that matters: after b3 b6 f4 h6 g4 the corner bishop is taken with Bxh1. The pawns on a2 and h2 both begin with no defender at all. The queen is on f1, the knights on b1 and e1, the rooks on c1 and g1.
Written from the measured facts above and checked against the board before publishing. All 960 positions have one.