Starting position #531
Back-rank setup: BRNKQNRB
SP-531 · ThroneGuard — Both knights start on inner files (b–g) while the king sits centrally on d or e — one of 204 positions filed here.
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 b1 and g1, the queen on e1.
Castling ends where it always does: king to g1 and rook to f1 on the short side, king to c1 and rook to d1 on the long one.
A bishop starts in the corner on a1: it has a single diagonal, which the b-pawn unlocks, running out to h8.
The pawn on c2 is defended by the king alone — the same soft spot f2 is in the classical setup.
The setup belongs to the ThroneGuard family; read right to left it becomes position 515.
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 81 Morozov Balance Index: 81 of 100 — class A — most balanced.
- Engine evaluation of the starting position: +13 centipawns for White (depth 47, 400 000 000 nodes).
- Rank 179 of 960 by balance — 1 is the most balanced start.
- In 50 self-play games White scored 54.0% (95% CI 40.4–67.0%).
- Balance band S — slight edge · dynamics along the play-out: equalizing
- Evaluation along the engine's main line (70 half-moves): +20 → 0 → +2 → 0
- Deeper check (1 200 000 000 nodes, depth 50): +5 cp, -8 cp against the base run — verified · E — even
Position facts
- Mirror twin: position #515
- The king starts on d, the rooks on b and g
- This position does not come up as the daily position in the next four years
Puzzles from this position
- Attack on the uncastled king: rook to h3 — Chess960 specifics · 780
- Attack on the uncastled king: pawn to f6 (e5·6) — Chess960 specifics · 780
- Winning blow: queen to f5 (f6) — Chess960 specifics · 780
- Winning blow: king to c1 (d1·8) — Chess960 specifics · 970
- Winning blow: knight to e6 (f4·8) — Chess960 specifics · 1150
- Winning blow: knight to a6 (b4·3) — Chess960 specifics · 1280
- Mate in 2: rook to b8 (b1·3) — Chess960 specifics · 1320
- Mate in 2: queen to c7 (c3·3) — Chess960 specifics · 1320
- Mate in 3: queen to b8 (c7) — Chess960 specifics · 1630
- Mate in 3: queen to c6 (h1·2) — Chess960 specifics · 1860
This position appears in course day 51
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Commentary
Both corners hold a bishop, a1 towards h8 and h1 towards a8, each with a single diagonal. The king begins on d1 with the queen beside him on e1, and castling is ordinary in both directions. On the second rank, c2 leans on the king alone; no other second-rank pawn starts short of a defender. The knights are on c1 and f1, the rooks on b1 and g1. The engine keeps the edge small, +13 centipawns: b3 b6 Nd3 f5 f4 Nd6.
Written from the measured facts above and checked against the board before publishing. All 960 positions have one.