Starting position #418
Back-rank setup: BRNQNBKR
SP-418 · RampartGuard — Both knights begin on inner files while the king sits on the wing (b/g); mirror twins stay together in 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 g1, the rooks on b1 and h1, the queen on d1.
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.
The pawn on f2 is defended by the king alone — the classic soft spot of the standard setup.
The setup belongs to the RampartGuard family; read right to left it becomes position 727.
The engine's main line opens with c4.
Every sentence here is computed from the setup itself and can be checked on the board.
Balance
MBI 100 Morozov Balance Index: 100 of 100 — class A — most balanced.
- Engine evaluation of the starting position: -2 centipawns for White (depth 47, 400 000 000 nodes).
- Rank 5 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: equalizing
- Evaluation along the engine's main line (46 half-moves): +22 → 0 → 0
- Deeper check (4 000 000 000 nodes, depth 55): +5 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 50.5% (95% CI 40.9–60.1%)
Position facts
- Mirror twin: position #727
- 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 50 days
Puzzles from this position
- Attack on the uncastled king: pawn to c5 (d4·17) — Chess960 specifics · 780
- Attack on the uncastled king: bishop to f6 (a1·9) — Chess960 specifics · 780
- Attack on the uncastled king: knight to c6 (e5·8) — Chess960 specifics · 920
- Winning blow: knight to d2 (f3) — Chess960 specifics · 970
- Winning blow: queen to e6 (g4·3) — Chess960 specifics · 1060
- Winning blow: rook to g7 (g3·5) — Chess960 specifics · 1200
- Mate in 2: knight to f8 — Chess960 specifics · 1220
- Attack on the uncastled king: queen to g6 (c2·3) — Chess960 specifics · 1280
- Mate in 3: queen to f7 (f5) — Chess960 specifics · 1630
- Attack on the uncastled king: pawn to h7 (g6·4) — Chess960 specifics · 2120
This position appears in course day 89
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Commentary
The engine's number lands on Black's side here, by the narrowest margin there is: -2 centipawns at depth 47. The king begins on g1, already on the square short castling would give him, so that castling moves the rook alone. A bishop is shut into the corner on a1 with a single diagonal to h8; the second bishop is on f1. Among the pawns, f2 leans on the king alone; no other second-rank pawn starts short of a defender. The queen is on d1, and the line runs c4 c5 e3 e6 Be2 Ncd6.
Written from the measured facts above and checked against the board before publishing. All 960 positions have one.