Starting position #81
Back-rank setup: BNNBRKRQ
SP-81 · BastionGuard — King shifted to c or f, knights kept clear of the edges — 168 positions in all.
Move the pieces right on the board — full Chess960 rules, castle by dropping the king on the rook.
Position features
The king starts on f1, the rooks on e1 and g1, the queen on h1.
Castling short simply swaps the two pieces: the king on f1 and the rook on g1 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 pawn on f2 is defended by the king alone — the classic soft spot of the standard setup.
The setup belongs to the BastionGuard family; read right to left it becomes position 875.
The engine's main line opens with g4.
Every sentence here is computed from the setup itself and can be checked on the board.
Balance
MBI 24 Morozov Balance Index: 24 of 100 — class C — noticeable edge.
- Engine evaluation of the starting position: +35 centipawns for White (depth 46, 400 000 000 nodes).
- Rank 743 of 960 by balance — 1 is the most balanced start.
- Balance band M — moderate edge · dynamics along the play-out: volatile
- Evaluation along the engine's main line (60 half-moves): +50 → 0 → 0 → -3
Position facts
- Mirror twin: position #875
- The king starts on f, the rooks on e and g
- King and rook are neighbours — castling from adjacent squares feels unusual
- This position does not come up as the daily position in the next four years
Puzzles from this position
- Attack on the uncastled king: bishop to h5 (f3·2) — Chess960 specifics · 780
- Attack on the uncastled king: queen to f3 (h1) — Chess960 specifics · 780
- Winning blow: queen to h2 (h1) — Chess960 specifics · 780
- Attack on the uncastled king: king to g2 (f1·6) — Chess960 specifics · 970
- Winning blow: rook to e7 (h7·3) — Chess960 specifics · 1200
- Attack on the uncastled king: queen to h6 (h8·2) — Chess960 specifics · 1200
- Winning blow: knight to e3 (d5) — Chess960 specifics · 1280
- Castling-960 to the rescue on g8 (f8·4) — Castling-960 · 1340
- Mate in 3: rook to e6 (e1·2) — Chess960 specifics · 1760
- Winning blow: knight to f6 (d5·17) — Chess960 specifics · 2100
This position appears in course day 25
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Commentary
Queen in one corner on h1, bishop in the other on a1 — the two furthest squares of the rank are both occupied by long-range pieces. Short castling swaps the king on f1 with the rook on g1. The bishop on d1 opens along the c-pawn and the e-pawn towards h5 and a4. On the second rank, f2 is defended by the king alone, exactly as in the classical setup. The line in the dataset opens g4 g5, then h4 h6 e3 e6.
Written from the measured facts above and checked against the board before publishing. All 960 positions have one.