Starting position #651
Back-rank setup: RNKRBQNB
SP-651 · 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 c1, the rooks on a1 and d1, the queen on f1.
The king already stands on c1, so castling long moves only the rook, from a1 to d1.
A bishop starts in the corner on h1: it has a single diagonal, which the g-pawn unlocks, running out to a8.
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 209.
The engine's main line opens with g4.
Every sentence here is computed from the setup itself and can be checked on the board.
Opening: main line
Stockfish's main line from the start of this setup, 15 moves deep (100 million nodes per move):
1. g4 g5 2. d4 e6 3. Nh3 Ne7 4. f4 h5 5. gxh5 g4 6. Ng5 Nbc6 7. e3 d5 8. h3 Nf5 9. Rd3 g3 10. a3 Qg8
Evaluation after the line: 0.00 for White.
Best first moves for White (evaluation in pawns):
- g4 — +0.40
- a4 — +0.40
- f4 — +0.27
Balance
MBI 43 Morozov Balance Index: 43 of 100 — class C — noticeable edge.
- Engine evaluation of the starting position: +28 centipawns for White (depth 46, 400 000 000 nodes).
- Rank 540 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): +49 → +57 → +46 → +7
Position facts
- Mirror twin: position #209
- The king starts on c, the rooks on a and d
- King and rook are neighbours — castling from adjacent squares feels unusual
- It becomes the daily position in 751 days
Puzzles from this position
- Winning blow: knight to e6 (g5·2) — Chess960 specifics · 920
- Attack on the uncastled king: knight to f3 (h4) — Chess960 specifics · 920
- Winning blow: rook to c3 (d3·2) — Chess960 specifics · 1200
- Winning blow: pawn to h6 (g5·3) — Chess960 specifics · 1200
- Attack on the uncastled king: queen to a6 (f1·6) — Chess960 specifics · 1220
- Winning blow: knight to e7 (f5·21) — Chess960 specifics · 1250
- Mate in 2: queen to c7 (b8) — Chess960 specifics · 1320
- Mate in 2: queen to b6 (c6) — Chess960 specifics · 1440
- Winning blow: queen to c6 (b5·11) — Chess960 specifics · 1790
- Winning blow: rook to c7 (c1·26) — Chess960 specifics · 1870
This position appears in course day 267
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Commentary
The king already stands on c1, so long castling moves the rook alone from d1. A bishop holds the corner on h1 with one diagonal to a8; the second bishop is on e1. On the second rank, h2 has no defender, and b2 and c2 both lean on the king alone. The queen is on f1, the knights on b1 and g1, the second rook in the corner on a1. The line in the dataset opens g4 g6, then d4 f5 Nc3 e6.
Written from the measured facts above and checked against the board before publishing. All 960 positions have one.