Starting position #500
Back-rank setup: RBBQNKNR
SP-500 · BastionGuard — A c- or f-file king and two knights on inner files (b–g).
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 d1.
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 b1 and c1; their long diagonals reach h7 and h6 once the c- and d-pawns step aside.
The pawn on f2 is defended by the king alone — the classic soft spot of the standard setup.
The setup belongs to the BastionGuard family; read right to left it becomes position 558.
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 96 Morozov Balance Index: 96 of 100 — class A — most balanced.
- Engine evaluation of the starting position: +8 centipawns for White (depth 46, 400 000 000 nodes).
- Rank 37 of 960 by balance — 1 is the most balanced start.
- Balance band E — even · dynamics along the play-out: equalizing
- Evaluation along the engine's main line (70 half-moves): +21 → +15 → +21 → +4 → 0
- Deeper check (1 200 000 000 nodes, depth 51): +8 cp, 0 cp against the base run — verified
Position facts
- Mirror twin: position #558
- The king starts on f, the rooks on a and h
- It becomes the daily position in 817 days
Puzzles from this position
- Attack on the uncastled king: queen to h8 (d4) — Chess960 specifics · 780
- Attack on the uncastled king: pawn to g4 (h3·11) — Chess960 specifics · 780
- Attack on the uncastled king: pawn to d6 (e5·13) — Chess960 specifics · 780
- Winning blow: rook to d6 (c6·4) — Chess960 specifics · 1150
- Mate in 2: queen to g7 (d4) — Chess960 specifics · 1220
- Mate in 2: bishop to g5 (e3·2) — Chess960 specifics · 1320
- Winning blow: rook to f3 (f1·11) — Chess960 specifics · 1610
- Mate in 3: knight to d5 (e7) — Chess960 specifics · 1630
- Mate in 3: king to h1 (g1·2) — Chess960 specifics · 1630
- Chess960 tactic on b7 (b1) — Chess960 specifics · 2400
This position appears in course day 33
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Commentary
The engine finds very little here — +8 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 b1 and c1, one on each colour. On the second rank, f2 leans on the king alone; no other second-rank pawn starts short of a defender. The queen is on d1, and both sides mirror each other for six half-moves: c4 c5 e4 e5 Ne2 Ne7.
Written from the measured facts above and checked against the board before publishing. All 960 positions have one.