Chess960 tactic on d6 (c4)
c9-11740naming 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.
Mate: a forcing sequence that ends the game — the king has no escape.
Mate in 4: a forced checkmate in four moves — every reply is covered.
A fork made possible by the Chess960 piece placement.
Difficulty 2400 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.
This is a forced mating attack. Start from the enemy king: which of its squares are already covered, and which move takes away the rest while keeping the king in check? Forcing moves — checks and captures — are what turn an attack into mate.
A mate in four is a longer forced net: each of your moves is a check or an irresistible threat, and the king is driven step by step to a square where it is finally trapped. Verify that the defender has exactly one reply at every branch.
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.
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 f2, queen e4, rook d1 g1, bishop d8, knight e2 c4, pawn a2 b2 g2 h2 d4.
Black: king f7, bishop f5, knight g6, pawn b4 c6 a7 g7 h7.
12 white and 8 black pieces are on the board; the puzzle position arises after move 21.
The position in numbers
White are ahead by 22 points of material (33 against 11; pawn = 1, knight and bishop = 3, rook = 5, queen = 9) — the tactic has to convert or outweigh that.
The white king stands on f2, the black king on f7.
It is White to move on move 21, with 56 legal replies to weigh — only the line that keeps the advantage solves the puzzle.
White keeps 5 pawns, Black 5. Files fully open (no pawns of either colour): e, f — natural highways for the rooks and queen. Half-open for White: c.
The White king has 5 empty squares to step to right now — the fewer they are, the closer a mating net.
Solution & explanation
Main line
21. Nd6+ Kg8 22. Qe8+ Nf8 23. Qf7+ Kh8 24. Qxf8#
Why it works
- Best move. knight to d6 is exactly what the engine plays (#3).
- Spot on — queen to e8 (#2).
- Precise: queen to f7 is the top choice (#1).
- Best move. queen to f8 is exactly what the engine plays (#).
- The line ends in a forced mate in 4.
- If instead Kg8, then Qe8+ and you stay on top.
Move by move
- 21. Nd6+ — knight to d6 with check
- Kg8 — king to g8
- 22. Qe8+ — queen to e8 with check
- Nf8 — knight to f8
- 23. Qf7+ — queen to f7 with check
- Kh8 — king to h8
- 24. Qxf8# — queen to f8 (capture) and it is checkmate
Types in this puzzle
Back-rank mate
The king is locked behind its own pawns — a heavy piece strikes the last rank.
The back-rank mate strikes a king locked behind its own unmoved pawns when a rook or queen crashes onto the last rank. The signs: no escape hole in front of the king, and the back rank guarded by a single piece or by nobody at all. Often that lone guard is deflected or traded off first, and only then comes the invasion. In your own games, make luft in time — one pawn move prevents a sudden catastrophe.
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.
Mate in 4+
A long forced mating combination.
Mate in four or longer is a marathon of forcing moves where the grip must never loosen. The tools are the same: checks, double threats and sacrifices that deny the opponent a single free tempo. Do not juggle the whole tree at once — walk the main line all the way to mate first, then verify the side branches. If somewhere the defender finds one quiet move that holds, your very first move was wrong.
About this position
These pieces come from starting position #294.
SP-294 · ThroneScout — King on a central file (d/e) with a knight starting on the rim (a/h).
The king starts on e1, the rooks on d1 and g1, the queen on a1.
The queenside rook already stands on d1, so castling long moves only the king, from e1 to c1.
The bishops stand on c1 and f1; their long diagonals reach h6 and a6 once the d- and e-pawns step aside.
The second rank carries 2 pawns with no defender at all: c2, h2.
The setup belongs to the ThroneScout family; read right to left it becomes position 374.
The engine's main line opens with c4.
Morozov Balance Index: 24 of 100 — class D — largest edge. Engine evaluation of the starting position: +35 centipawns for White (depth 46, 400 000 000 nodes).
Explore position #294Provenance
Mined from the project's engine self-play games.
Pack 015 · SP-294
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