Winning blow: queen to b7 (a7·5)
c9-09610naming tag (square·N)Opens in the app if installed, otherwise downloads the APK.
The tactical motive
Chess960 twist: use the unusual starting setup of the pieces.
A fork made possible by the Chess960 piece placement.
Winning tactic: there is a move that gains a decisive advantage — find it.
Difficulty 1290 ShuffleRating — club-player level.
White to move — find the best continuation
How to recognize this tactic
In Chess960 the pieces start on unfamiliar squares, so tactics appear earlier and from unusual angles. Do not trust classical patterns — read the actual lines of the bishops, the rooks and the queen from where they really stand in this position.
A set-up fork needs one preparing move before the fork lands — a check that drives the king onto the forking square, or a capture that lines the targets up. Find the preparation first, then the fork it makes possible.
This position hides a concrete tactic that wins material or mates. Start with the most forcing candidate moves — checks, captures and threats — and calculate each to a clear end before choosing; the winning line is usually the one the opponent cannot meet.
General method: before you move, list the forcing candidates — every check, every capture, every direct threat — and calculate those first. The solution to a tactic is almost always among them.
Position on the board
White: king e2, queen a7, bishop c1 c6, knight c2, pawn h2 b3 g3 c4 f4.
Black: king c8, queen f8, bishop h8, knight c7 g8, pawn f5 d6 e6 g6.
10 white and 9 black pieces are on the board; the puzzle position arises after move 21.
The position in numbers
White are ahead by 1 points of material (23 against 22; pawn = 1, knight and bishop = 3, rook = 5, queen = 9) — the tactic has to convert or outweigh that.
The white king stands on e2, the black king on c8.
It is White to move on move 21, with 50 legal replies to weigh — only the line that keeps the advantage solves the puzzle.
White keeps 5 pawns, Black 4. Files fully open (no pawns of either colour): a — natural highways for the rooks and queen. Half-open for White: d, e.
White hold the bishop pair, an edge in open lines. The White king has 8 empty squares to step to right now — the fewer they are, the closer a mating net.
Solution & explanation
Main line
21. Qb7+ Kd8 22. Qb8+ Ke7 23. Qxc7+
Why it works
- Great move! queen to b7 keeps the pressure (#6).
- Well found: queen to b8 (#5).
- Strong! queen to c7 is the sharp choice (#4).
- You win a piece — the knight.
- If instead Kd8, then Qb8+ and you stay on top.
Move by move
- 21. Qb7+ — queen to b7 with check
- Kd8 — king to d8
- 22. Qb8+ — queen to b8 with check
- Ke7 — king to e7
- 23. Qxc7+ — queen to c7 (capture) with check
Types in this puzzle
Setup fork
The random setup allows a fork that classical chess never sees.
A setup fork is a double attack that exists only because of the unusual starting squares — in classical chess these targets never stand side by side. Look for pairs of undefended pieces on your opponent's back rank and for squares from which a knight or pawn hits both at once. Such forks usually appear within the first moves, before the pieces disperse. In every new position, note right away which starting pieces are defended by no one.
Check chase
Every move is a check — the king is chased into losing ground.
In a check chase every one of your moves is a check, so the opponent never gets a free second. The king is herded across the board until it loses a piece or walks into a decisive blow. Such lines are the easiest to calculate: each check allows only a handful of replies, so try them all. Make it a habit to start calculating any sharp position with the checks — they are the most forcing moves on the board.
About this position
These pieces come from starting position #343.
SP-343 · ThroneScout — A central king (d or e), but with a knight posted out on the a- or h-file.
The king starts on d1, the rooks on b1 and f1, the queen on e1.
The kingside rook already stands on f1, so castling short moves only the king, from d1 to g1.
A bishop starts in the corner on h1: it has a single diagonal, which the g-pawn unlocks, running out to a8.
The second rank carries 2 pawns with no defender at all: a2, h2.
The setup belongs to the ThroneScout family; read right to left it becomes position 322.
The engine's main line opens with d3.
Morozov Balance Index: 93 of 100 — class A — most balanced. Engine evaluation of the starting position: +11 centipawns for White (depth 46, 400 000 000 nodes).
Explore position #343Provenance
Mined from the project's engine self-play games.
Pack 009 · SP-343
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