Starting position #823
Back-rank setup: RKBNQRNB
SP-823 · RampartGuard — The king starts out on a wing file, b or g, 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 b1, the rooks on a1 and f1, the queen on e1.
From b1 the king makes the longest journey Chess960 allows when castling short: five squares to g1.
A bishop starts in the corner on h1: it has a single diagonal, which the g-pawn unlocks, running out to a8.
One second-rank pawn starts with no defender at all: h2.
The setup belongs to the RampartGuard family; read right to left it becomes position 130.
The engine's main line opens with a4.
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: -5 centipawns for White (depth 44, 400 000 000 nodes).
- Rank 1 of 960 by balance — 1 is the most balanced start.
- In 50 self-play games White scored 52.0% (95% CI 38.5–65.2%).
- Balance band E — even · dynamics along the play-out: stable
- Evaluation along the engine's main line (70 half-moves): +37 → +15 → 0 → 0
- Deeper check (4 000 000 000 nodes, depth 60): 0 cp, +5 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 51.5% (95% CI 41.8–61.1%)
Position facts
- Mirror twin: position #130
- The king starts on b, the rooks on a and f
- King and rook are neighbours — castling from adjacent squares feels unusual
- It becomes the daily position in 192 days
Puzzles from this position
- Attack on the uncastled king: queen to e7 (b4) — Chess960 specifics · 780
- Winning blow: bishop to c6 (b5) — Chess960 specifics · 920
- Attack on the uncastled king: pawn to c4 (d3·36) — Chess960 specifics · 920
- Winning blow: queen to a6 (c4) — Chess960 specifics · 1010
- Winning blow: rook to b8 (b3·4) — Chess960 specifics · 1200
- Winning blow: rook to b7 (b3·3) — Chess960 specifics · 1290
- Attack on the uncastled king: king to a2 (b1·11) — Chess960 specifics · 1390
- Attack on the uncastled king: queen to a3 (a1·4) — Chess960 specifics · 1610
- Mate in 3: pawn to d6 (d5·2) — Chess960 specifics · 1760
- Winning blow: pawn to e6 (e5·19) — Chess960 specifics · 2060
This position appears in course day 74
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Commentary
The king begins on b1, and the rook already occupies f1, so short castling is a solo five-square walk to g1. A bishop holds the corner on h1 with one diagonal to a8; the second bishop is on c1. The pawn on h2 begins without a defender, and the pawn on c2 leans on the king alone. The queen is on e1, the knights on d1 and g1, the second rook on a1. Here the engine's number sits below zero, -5 centipawns: White moves first and the search still reads the start as a shade in Black's favour, with the line a4 d6 f4 f5 Nf3 a5.
Written from the measured facts above and checked against the board before publishing. All 960 positions have one.