Winning blow: pawn to a8 (a7·9)
c9-18555naming 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 2060 ShuffleRating — expert level — few solve it at first try.
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 h8, rook a1, bishop e1, knight d2, pawn b2 f2 e3 c4 g4 a7.
Black: king e7, queen g1, rook f3, bishop e8, pawn e5 g5 d6 f7.
11 white and 8 black pieces are on the board; the puzzle position arises after move 23.
The position in numbers
White are ahead by 5 points of material (26 against 21; 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 e7.
It is White to move on move 23, with 37 legal replies to weigh — only the line that keeps the advantage solves the puzzle.
White keeps 6 pawns, Black 4. Files fully open (no pawns of either colour): h — natural highways for the rooks and queen. Half-open for White: d.
The White king has 3 empty squares to step to right now — the fewer they are, the closer a mating net.
Solution & explanation
Main line
23. a8=Q Rxf2+ 24. Bxf2 Qxg4+ 25. Ke1
Why it works
- Sensible development: pawn to a8.
- Spot on — bishop to f2 (#6).
- A natural move: king to e1.
- You win a piece — the rook.
- If instead Rxf2+, then Bxf2 and you win the rook.
Move by move
- 23. a8=Q — pawn to a8
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.
Pawn fork
A humble pawn steps forward and attacks two pieces at once.
A pawn fork is a single pawn step that attacks two pieces at once. Since the pawn is the cheapest unit on the board, the trade is always a bargain — the opponent saves only one of the two targets. The pattern: two enemy pieces on the same rank, one file apart, with a square for your pawn between them. Before parking your pieces near enemy pawns, always ask whether one little push forks them both.
Promotion
The pawn reaches the last rank and becomes a queen — decisively.
Promotion turns a pawn on the last rank into a queen and rewrites the evaluation on the spot. In tactics the passer rarely walks in for free — usually a sacrifice clears its path. Count the tempi: how many moves does the pawn need, and can the defender stop it in time? And watch the promotion square itself — it must be out of enemy reach or won by force in your combination.
About this position
These pieces come from starting position #443.
SP-443 · BastionGuard — Off-centre king (c/f), no knight on the a- or h-file.
The king starts on f1, the rooks on a1 and g1, the queen on d1.
Castling short simply swaps the two pieces: the king on f1 and the rook on g1 trade places.
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: b2, h2.
The setup belongs to the BastionGuard family; read right to left it becomes position 705.
The engine's main line opens with c4.
Morozov Balance Index: 98 of 100 — class A — most balanced. Engine evaluation of the starting position: +5 centipawns for White (depth 47, 400 000 000 nodes).
Explore position #443Provenance
Mined from the project's engine self-play games.
Pack 015 · SP-443
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