Chess960 tactic on c4
c9-10136Opens 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 2120 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 h2, queen a2, rook f6, bishop c3, knight f5, pawn f2 g2 a3 f3 b5.
Black: king g8, queen d1, rook d3, knight b8, pawn c4 b6 g6 a7 h7.
10 white and 9 black pieces are on the board; the puzzle position arises after move 31.
The position in numbers
White are ahead by 3 points of material (25 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 h2, the black king on g8.
It is White to move on move 31, with 37 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): d, e — natural highways for the rooks and queen. Half-open for White: c, h.
The White king has 2 empty squares to step to right now — the fewer they are, the closer a mating net.
Solution & explanation
Main line
31. Qxc4+ Rd5 32. Qc8+ Rd8 33. Qe6+ Kh8 34. Rf8#
Why it works
- Best move. queen to c4 is exactly what the engine plays (#3).
- Spot on — queen to c8 (#2).
- Precise: queen to e6 is the top choice (#1).
- Best move. rook to f8 is exactly what the engine plays (#).
- The line ends in a forced mate in 4.
- If instead Rd5, then Qc8+ and you stay on top.
Move by move
- 31. Qxc4+ — queen to c4 (capture) with check
- Rd5 — rook to d5
- 32. Qc8+ — queen to c8 with check
- Rd8 — rook to d8
- 33. Qe6+ — queen to e6 with check
- Kh8 — king to h8
- 34. Rf8# — rook to f8 and it is checkmate
Types in this puzzle
Double-check mate
Double check leaves only king moves — and there are none.
The double-check mate ends the game with check from two pieces at once, leaving the king with nothing. Neither capturing nor blocking works against a double check — only a king move, and here there is none. Look for a discovered check where the front piece checks too: it may even land on a defended square with total impunity. That is why the double check crowns so many of the most beautiful sacrificial combinations.
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 #18.
SP-18 · RampartGuard — King on the wing (b/g) with both knights on inner files.
The king starts on g1, the rooks on e1 and h1, the queen on c1.
The king already stands on its castled square, so castling short moves only the rook, from h1 to f1.
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: a2.
The setup belongs to the RampartGuard family; read right to left it becomes position 935.
The engine's main line opens with d4, putting a pawn straight into the centre.
Morozov Balance Index: 3 of 100 — class D — largest edge. Engine evaluation of the starting position: +52 centipawns for White (depth 45, 400 000 000 nodes).
Explore position #18Provenance
Mined from the project's engine self-play games.
Pack 015 · SP-18
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