Starting position #401
Back-rank setup: BRQBNNKR
SP-401 · RampartGuard — A wing king (b/g) with 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 g1, the rooks on b1 and h1, the queen on c1.
The king already stands on its castled square, so castling short moves only the rook, from h1 to f1.
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 RampartGuard family; read right to left it becomes position 747.
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 96 Morozov Balance Index: 96 of 100 — class A — most balanced.
- Engine evaluation of the starting position: -7 centipawns for White (depth 41, 400 000 000 nodes).
- Rank 39 of 960 by balance — 1 is the most balanced start.
- In 50 self-play games White scored 49.0% (95% CI 35.7–62.4%).
- Balance band E — even · dynamics along the play-out: stable
- Evaluation along the engine's main line (62 half-moves): +30 → -8 → 0 → 0
- Deeper check (4 000 000 000 nodes, depth 54): 0 cp, +7 cp against the base run — verified
- Sign verdict: even — within engine noise
- Self-play v2: 100 games at 1 000 000 nodes per move — White scored 49.0% (95% CI 39.4–58.7%)
Position facts
- Mirror twin: position #747
- The king starts on g, the rooks on b and h
- King and rook are neighbours — castling from adjacent squares feels unusual
- It becomes the daily position in 679 days
Puzzles from this position
- Attack on the uncastled king: bishop to d4 — Chess960 specifics · 780
- Attack on the uncastled king: pawn to e4 (d3·11) — Chess960 specifics · 780
- Attack on the uncastled king: queen to g7 (b2·3) — Chess960 specifics · 850
- Winning blow: knight to f5 (g3·5) — Chess960 specifics · 920
- Winning blow: king to f1 (g1·20) — Chess960 specifics · 970
- Mate in 2: knight to g6 (e7) — Chess960 specifics · 1220
- Attack on the uncastled king: queen to g7 (a1·12) — Chess960 specifics · 1320
- Attack on the uncastled king: queen to f5 (g5) — Chess960 specifics · 1390
- Mate in 3: rook to h4 (d4) — Chess960 specifics · 1630
- Mate in 3: queen to h7 (e4·2) — Chess960 specifics · 2170
This position appears in course day 37
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Commentary
This is one of the rare starts where the engine's number lands on Black's side: -7 centipawns at depth 41 — a hair on the scale of a whole game. The king begins on g1, already on the square short castling would give him, so that castling moves the rook alone. A bishop is closed into the corner on a1 with a single diagonal to h8; the second bishop is on d1. Among the pawns, a2 has no defender, and f2 leans on the king alone. The line runs b4 b6 h4 c5 h5 h6.
Written from the measured facts above and checked against the board before publishing. All 960 positions have one.