Starting position #521
Back-rank setup: RNQBBKNR
SP-521 · BastionGuard — Off-centre king (c/f), 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 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 e1; their long diagonals reach h5 and a5 once the e- and d-pawns step aside.
The pawn on g2 is defended by the king alone — the same soft spot f2 is in the classical setup.
The setup belongs to the BastionGuard family; read right to left it becomes position 537.
The engine's main line opens with d4, 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 95 Morozov Balance Index: 95 of 100 — class A — most balanced.
- Engine evaluation of the starting position: +9 centipawns for White (depth 47, 400 000 000 nodes).
- Rank 44 of 960 by balance — 1 is the most balanced start.
- Balance band E — even · dynamics along the play-out: stable
- Evaluation along the engine's main line (70 half-moves): +30 → +15 → +17 → +9 → 0
- Deeper check (1 200 000 000 nodes, depth 50): +20 cp, +11 cp against the base run — not confirmed at depth · S — slight edge
Position facts
- Mirror twin: position #537
- The king starts on f, the rooks on a and h
- It becomes the daily position in 1060 days
Puzzles from this position
- Attack on the uncastled king: pawn to e6 (d5·6) — Chess960 specifics · 780
- Attack on the uncastled king: rook to c1 (a1·2) — Chess960 specifics · 780
- Attack on the uncastled king: bishop to a5 (e1·14) — Chess960 specifics · 780
- Attack on the uncastled king: queen to d6 (f4) — Chess960 specifics · 920
- Winning blow: king to e3 (f2·2) — Chess960 specifics · 970
- Winning blow: queen to f8 (e8) — Chess960 specifics · 1150
- Winning blow: queen to h8 (e5·2) — Chess960 specifics · 1280
- Mate in 2: queen to e8 (d8) — Chess960 specifics · 1320
- Mate in 3: rook to g6 (d6) — Chess960 specifics · 1630
- Winning blow: knight to f6 (d5·18) — Chess960 specifics · 2100
This position appears in course day 59
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Commentary
The engine finds very little here — +9 centipawns. Castling is ordinary in both directions from f1, with the rooks in the corners on a1 and h1. The bishops stand side by side on d1 and e1, one on each colour. Among the pawns, g2 leans on the king alone; no other second-rank pawn starts short of a defender. The queen is on c1, and the d-pawn goes two squares up: d4 c5 d5 Nf6 c4 b5.
Written from the measured facts above and checked against the board before publishing. All 960 positions have one.