Starting position #485
Back-rank setup: QRBBNKNR
SP-485 · 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 f1, the rooks on b1 and h1, the queen on a1.
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.
The bishops stand on c1 and d1; their long diagonals reach h6 and h5 once the d- and e-pawns step aside.
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 570.
The engine's main line opens with b4.
Every sentence here is computed from the setup itself and can be checked on the board.
Balance
MBI 99 Morozov Balance Index: 99 of 100 — class A — most balanced.
- Engine evaluation of the starting position: +3 centipawns for White (depth 44, 400 000 000 nodes).
- Rank 10 of 960 by balance — 1 is the most balanced start.
- In 50 self-play games White scored 51.0% (95% CI 37.6–64.3%).
- Balance band E — even · dynamics along the play-out: stable
- Evaluation along the engine's main line (67 half-moves): +29 → +23 → +33 → 0
- Deeper check (1 200 000 000 nodes, depth 50): +1 cp, -2 cp against the base run — verified
Position facts
- Mirror twin: position #570
- The king starts on f, the rooks on b and h
- It becomes the daily position in 1441 days
Puzzles from this position
- Winning blow: queen to h7 — Chess960 specifics · 780
- Attack on the uncastled king: pawn to c6 (b5·8) — Chess960 specifics · 780
- Attack on the uncastled king: bishop to a6 (d3·2) — Chess960 specifics · 780
- Attack on the uncastled king: rook to b5 — Chess960 specifics · 780
- Attack on the uncastled king: queen to f7 (a2·3) — Chess960 specifics · 850
- Winning blow: king to h2 (h1) — Chess960 specifics · 920
- Attack on the uncastled king: queen to a2 (a1·8) — Chess960 specifics · 1060
- Winning blow: queen to c1 (a3) — Chess960 specifics · 1200
- Mate in 2: knight to d3 (e1·2) — Chess960 specifics · 1440
- Winning blow: queen to h6 (f6·2) — Chess960 specifics · 2060
This position appears in course day 47
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Commentary
The engine puts this start at +3 centipawns — about as close to level as a game of chess begins. Castling is ordinary in both directions from f1, with the rooks on b1 and h1. The bishops stand side by side on c1 and d1, one on each colour. Among the pawns, f2 leans on the king alone; no other second-rank pawn starts short of a defender. The queen begins in the far corner on a1, and the line runs b4 b6 c4 c5 e3 Ngf6.
Written from the measured facts above and checked against the board before publishing. All 960 positions have one.