Starting position #99
Back-rank setup: BQNRNKRB
SP-99 · 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 d1 and g1, the queen on b1.
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.
One second-rank pawn starts with no defender at all: h2.
The setup belongs to the BastionGuard family; read right to left it becomes position 851.
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 80 Morozov Balance Index: 80 of 100 — class A — most balanced.
- Engine evaluation of the starting position: +17 centipawns for White (depth 46, 400 000 000 nodes).
- Rank 206 of 960 by balance — 1 is the most balanced start.
- Balance band S — slight edge · dynamics along the play-out: equalizing
- Evaluation along the engine's main line (60 half-moves): +18 → +20 → +11 → +4
Position facts
- Mirror twin: position #851
- The king starts on f, the rooks on d and g
- King and rook are neighbours — castling from adjacent squares feels unusual
- It becomes the daily position in 1231 days
Puzzles from this position
- Attack on the uncastled king: queen to h8 (a1·2) — Chess960 specifics · 620
- Attack on the uncastled king: rook to g6 — Chess960 specifics · 780
- Attack on the uncastled king: pawn to h4 (g3·8) — Chess960 specifics · 780
- Attack on the uncastled king: rook to f7 (h7) — Chess960 specifics · 850
- Winning blow: rook to a1 (c1) — Chess960 specifics · 920
- Winning blow: queen to g7 (h6·6) — Chess960 specifics · 1290
- Winning blow: knight to d5 (c3·17) — Chess960 specifics · 1340
- Winning blow: queen to e7 (f7·3) — Chess960 specifics · 1560
- Winning blow: rook to d8 (d7·6) — Chess960 specifics · 1700
- Chess960 tactic on g5 (f7·2) — Chess960 specifics · 2400
This position appears in course day 8
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Commentary
Short castling swaps the king on f1 with the rook on g1; long castling moves the king alone, since the rook already occupies d1. Both corners hold a bishop, a1 towards h8 and h1 towards a8, each with a single diagonal. The queen stands on b1, the knights on c1 and e1. On the second rank, h2 begins with no defender at all, and f2 has only the king. The line in the dataset opens b4 b5, then Nb3 Nb6 d3, and Black castles: O-O.
Written from the measured facts above and checked against the board before publishing. All 960 positions have one.