Starting position #429
Back-rank setup: RNQBNKBR
SP-429 · 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 a1 and h1, the queen on c1.
Castling ends where it always does: king to g1 and rook to f1 on the short side, king to c1 and rook to d1 on the long one.
The bishops stand on d1 and g1; their long diagonals reach h5 and a7 once the e- and f-pawns step aside.
Every pawn on the second rank is defended from the very first move.
The setup belongs to the BastionGuard family; read right to left it becomes position 728.
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 100 Morozov Balance Index: 100 of 100 — class A — most balanced.
- Engine evaluation of the starting position: 0 centipawns for White (depth 50, 400 000 000 nodes).
- Rank 4 of 960 by balance — 1 is the most balanced start.
- In 50 self-play games White scored 50.0% (95% CI 36.6–63.4%).
- Balance band E — even · dynamics along the play-out: equalizing
- Evaluation along the engine's main line (70 half-moves): +22 → +30 → +21 → 0
- Deeper check (4 000 000 000 nodes, depth 53): +10 cp, +10 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 51.0% (95% CI 41.3–60.6%)
Position facts
- Mirror twin: position #728
- The king starts on f, the rooks on a and h
- It becomes the daily position in 1418 days
Puzzles from this position
- Attack on the uncastled king: pawn to g5 — Chess960 specifics · 780
- Attack on the uncastled king: pawn to c4 (d3·6) — Chess960 specifics · 780
- Attack on the uncastled king: pawn to d5 (e4·47) — Chess960 specifics · 780
- Attack on the uncastled king: pawn to d5 (c4·64) — Chess960 specifics · 780
- Attack on the uncastled king: rook to a2 (a1·8) — Chess960 specifics · 780
- Winning blow: queen to b8 (a7) — Chess960 specifics · 920
- Attack on the uncastled king: bishop to c5 (f2·5) — Chess960 specifics · 1090
- Attack on the uncastled king: knight to g6 (f4·9) — Chess960 specifics · 1320
- Mate in 3: queen to e6 (e3·2) — Chess960 specifics · 1630
- Winning blow: queen to f5 (c8·3) — Chess960 specifics · 1790
This position appears in course day 30
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Commentary
Two things line up here: every pawn on the second rank begins with a defender, and after a search to depth 50 the engine calls the position dead level — +0 centipawns. Castling is ordinary in both directions from f1, with the rooks in the corners on a1 and h1. The bishops are on d1 and g1, the queen on c1. The knights are on b1 and e1. The engine takes the centre with e4 and the line runs e4 c5 f4 d6 Be3 f5.
Written from the measured facts above and checked against the board before publishing. All 960 positions have one.