Starting position #665
Back-rank setup: RNKBBRNQ
SP-665 · BastionGuard — Off-centre king (c/f), no knight on the a- or h-file.
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 a1 and f1, the queen on h1.
The king already stands on c1, so castling long moves only the rook, from a1 to d1.
The bishops stand on d1 and e1; their long diagonals reach h5 and a5 once the e- and d-pawns step aside.
The pawn on b2 is defended by the king alone — the same soft spot f2 is in the classical setup.
The setup belongs to the BastionGuard family; read right to left it becomes position 201.
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 42 Morozov Balance Index: 42 of 100 — class C — noticeable edge.
- Engine evaluation of the starting position: +22 centipawns for White (depth 44, 400 000 000 nodes).
- Rank 558 of 960 by balance — 1 is the most balanced start.
- In 50 self-play games White scored 56.0% (95% CI 42.3–68.8%).
- Balance band S — slight edge · dynamics along the play-out: equalizing
- Evaluation along the engine's main line (41 half-moves): +45 → 0 → 0
Position facts
- Mirror twin: position #201
- The king starts on c, the rooks on a and f
- It becomes the daily position in 391 days
Puzzles from this position
- Attack on the uncastled king: queen to d5 (h1) — Chess960 specifics · 780
- Attack on the uncastled king: rook to f7 (f1) — Chess960 specifics · 780
- Attack on the uncastled king: queen to g1 (h1·3) — Chess960 specifics · 970
- Attack on the uncastled king: queen to h5 (e2·4) — Chess960 specifics · 1010
- Winning blow: queen to c7 (e7·2) — Chess960 specifics · 1010
- Mate in 2: knight to b8 — Chess960 specifics · 1220
- Winning blow: bishop to g4 (e2·7) — Chess960 specifics · 1560
- Mate in 3: bishop to g4 (d1·3) — Chess960 specifics · 1630
- Mate in 3: queen to d6 (b8) — Chess960 specifics · 1760
- Chess960 tactic on d6 (f5) — Chess960 specifics · 2120
This position appears in course day 218
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Commentary
Both castlings are half-moves here: the king already stands on c1 for the long one, and the rook already occupies f1 for the short. The bishops stand side by side on d1 and e1, one on each colour. Among the pawns, b2 leans on the king alone; no other second-rank pawn starts short of a defender. The queen begins in the far corner on h1, the knights on b1 and g1, the second rook in the corner on a1. The engine opens on the kingside: g4 e6 h4 f6 Nh3 g5.
Written from the measured facts above and checked against the board before publishing. All 960 positions have one.