Starting position #946
Back-rank setup: BRKRNBNQ
SP-946 · BastionGuard — Both knights begin inside the board while the king stands on c or f; a position and its mirror twin share this family.
Move the pieces right on the board — full Chess960 rules, castle by dropping the king on the rook.
Position features
The king starts on c1, the rooks on b1 and d1, the queen on h1.
The king already stands on c1, so castling long moves only the rook, from b1 to d1.
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, f2.
The setup belongs to the BastionGuard family; read right to left it becomes position 7.
The engine's main line opens with g3.
Every sentence here is computed from the setup itself and can be checked on the board.
Balance
MBI 28 Morozov Balance Index: 28 of 100 — class C — noticeable edge.
- Engine evaluation of the starting position: +33 centipawns for White (depth 43, 400 000 000 nodes).
- Rank 682 of 960 by balance — 1 is the most balanced start.
- Balance band M — moderate edge · dynamics along the play-out: stable
- Evaluation along the engine's main line (60 half-moves): +35 → +9 → +4 → 0
Position facts
- Mirror twin: position #7
- The king starts on c, the rooks on b and d
- 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: queen to e8 — Chess960 specifics · 620
- Attack on the uncastled king: bishop to h8 (a1·9) — Chess960 specifics · 780
- Winning blow: pawn to b6 (c5·2) — Chess960 specifics · 920
- Winning blow: bishop to d6 (e5·2) — Chess960 specifics · 1010
- Winning blow: knight to d7 (c5·12) — Chess960 specifics · 1200
- Winning blow: queen to b6 (a6·4) — Chess960 specifics · 1200
- Winning blow: queen to f1 (f2·3) — Chess960 specifics · 1340
- Attack on the uncastled king: knight to b6 (c4·4) — Chess960 specifics · 1630
- Winning blow: pawn to c6 (b5·12) — Chess960 specifics · 1700
- Chess960 tactic on b7 (e4·4) — Chess960 specifics · 2400
This position appears in course day 6
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Commentary
The king already stands on c1, so long castling moves the rook alone; the rooks are on b1 and d1. The queen begins in the corner on h1, and a bishop holds the opposite corner on a1 with its one diagonal to h8; the second bishop is on f1. Two pawns begin without a defender, a2 and f2. The knights are on e1 and g1 — both can reach f3, so a knight move there has to name its file, though the line sends one to d3 instead. White's edge is +33 centipawns: g3 g6 e4 e5 Nd3 f5.
Written from the measured facts above and checked against the board before publishing. All 960 positions have one.