Starting position #850
Back-rank setup: BRKNRBNQ
SP-850 · 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 e1, 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.
One second-rank pawn starts with no defender at all: a2.
The setup belongs to the BastionGuard family; read right to left it becomes position 103.
The engine's main line opens with e4, putting a pawn straight into the centre.
Every sentence here is computed from the setup itself and can be checked on the board.
Balance
MBI 31 Morozov Balance Index: 31 of 100 — class C — noticeable edge.
- Engine evaluation of the starting position: +32 centipawns for White (depth 43, 400 000 000 nodes).
- Rank 658 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): +47 → +28 → +33 → +19
Position facts
- Mirror twin: position #103
- The king starts on c, the rooks on b and e
- King and rook are neighbours — castling from adjacent squares feels unusual
- It becomes the daily position in 1076 days
Puzzles from this position
- Attack on the uncastled king: queen to d4 (a7) — Chess960 specifics · 970
- Winning blow: knight to b6 (c4·5) — Chess960 specifics · 1060
- Winning blow: knight to d6 (b5·8) — Chess960 specifics · 1150
- Winning blow: king to b1 (c1·21) — Chess960 specifics · 1200
- Attack on the uncastled king: rook to e8 (e3·2) — Chess960 specifics · 1280
- Winning blow: queen to c1 (a3·2) — Chess960 specifics · 1340
- Mate in 3: pawn to c5 — Chess960 specifics · 1630
- Attack on the uncastled king: king to d2 (c1·11) — Chess960 specifics · 1750
- Winning blow: rook to d6 (d5·7) — Chess960 specifics · 1870
- Chess960 tactic on e6 (d5·3) — Chess960 specifics · 2350
This position appears in course day 236
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Commentary
The king already stands on c1, so long castling moves the rook alone; the rooks are on b1 and e1. 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. Among the pawns, a2 begins without a defender, and the pawns on c2 and d2 lean on the king alone. The knights are on d1 and g1, and their reaches do not overlap, so the line writes Nf3 and Nc3 with no file letter. White's edge is +32 centipawns: e4 e5 Nf3 h5 Nc3 f6.
Written from the measured facts above and checked against the board before publishing. All 960 positions have one.