Starting position #481
Back-rank setup: BQRBNKNR
SP-481 · BastionGuard — The king starts one file off-centre, on c or f, with neither knight in a corner.
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 c1 and h1, the queen on b1.
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.
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: d2.
The setup belongs to the BastionGuard family; read right to left it becomes position 571.
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 99 Morozov Balance Index: 99 of 100 — class A — most balanced.
- Engine evaluation of the starting position: +5 centipawns for White (depth 48, 400 000 000 nodes).
- Rank 11 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 (70 half-moves): +21 → 0 → -1 → 0
- Deeper check (1 200 000 000 nodes, depth 54): +12 cp, +7 cp against the base run — verified · S — slight edge
Position facts
- Mirror twin: position #571
- The king starts on f, the rooks on c and h
- It becomes the daily position in 409 days
Puzzles from this position
- Attack on the uncastled king: pawn to e4 (d3·36) — Chess960 specifics · 780
- Attack on the uncastled king: pawn to c3 (d2·7) — Chess960 specifics · 780
- Attack on the uncastled king: queen to g5 (b5) — Chess960 specifics · 780
- Winning blow: queen to c3 (g3) — Chess960 specifics · 1010
- Winning blow: rook to e8 (b8) — Chess960 specifics · 1060
- Winning blow: queen to h8 (h6) — Chess960 specifics · 1200
- Mate in 2: knight to g6 (e5·2) — Chess960 specifics · 1320
- Winning blow: rook to b1 (g1) — Chess960 specifics · 1390
- Mate in 3: rook to d8 (c8) — Chess960 specifics · 1630
- Winning blow: queen to f7 (f1·6) — Chess960 specifics · 2100
This position appears in course day 46
In your browser or in the Android app. Nothing to install · Free, no ads
Commentary
The engine finds almost nothing for White here: +5 centipawns at depth 48. Castling is ordinary in both directions from f1, with the rooks on c1 and h1. A bishop is closed into the corner on a1 with a single diagonal to h8; the second bishop is on d1. The pawn on d2 has no defender, and f2 leans on the king alone. The queen is on b1, and the b-file opens for both: c4 c5 b4 b6 bxc5 bxc5.
Written from the measured facts above and checked against the board before publishing. All 960 positions have one.