Chess960 tactic on b1 (f1)
c9-15596naming 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.
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.
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 g1, queen a6, rook f1, bishop a1 e2, knight h1 d2, pawn a2 f2 e3 g3 h3 d4.
Black: king b8, queen e7, rook d8 g8, bishop d5 d6, knight h4, pawn c5 e6 d7 f7 g7 h7.
13 white and 13 black pieces are on the board; the puzzle position arises after move 20.
The position in numbers
Black are ahead by 2 points of material (32 against 34; pawn = 1, knight and bishop = 3, rook = 5, queen = 9) — the tactic has to convert or outweigh that.
The white king stands on g1, the black king on b8.
It is White to move on move 20, with 40 legal replies to weigh — only the line that keeps the advantage solves the puzzle.
White keeps 6 pawns, Black 6. Files fully open (no pawns of either colour): b — natural highways for the rooks and queen. Half-open for White: c.
The White king has 1 empty squares to step to right now — the fewer they are, the closer a mating net.
Solution & explanation
Main line
20. Rb1+ Kc7 21. Qb6+ Kc8 22. Ba6+ Bb7 23. Qxb7#
Why it works
- Best move. rook to b1 is exactly what the engine plays (#3).
- Spot on — queen to b6 (#2).
- Precise: bishop to a6 is the top choice (#1).
- Best move. queen to b7 is exactly what the engine plays (#).
- The line ends in a forced mate in 4.
- If instead Kc7, then Qb6+ and you stay on top.
Move by move
- 20. Rb1+ — rook to b1 with check
- Kc7 — king to c7
- 21. Qb6+ — queen to b6 with check
- Kc8 — king to c8
- 22. Ba6+ — bishop to a6 with check
- Bb7 — bishop to b7
- 23. Qxb7# — queen to b7 (capture) and it is checkmate
Types in this puzzle
Supported queen mate
The queen delivers mate face to face, protected by a friend.
The supported queen mate is the most common pattern of all: the queen lands next to the king and mates because a friendly piece or pawn protects her. The king is helpless — capturing is impossible, and the queen covers every neighboring square herself. Hunt for a protected square beside the enemy king: a knight, bishop or pawn eyeing it turns her invasion into mate. Verify one thing — that the square really is defended, or the king eats her.
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.
Win the pinned piece
The pinned piece cannot run — attack it again and win it.
A pinned piece cannot flee, which means you can win it outright by attacking it one more time. Count attackers against defenders: if you outnumber them, the piece is yours. The best extra attacker is a pawn, since it costs less than anything it might capture. Do not rush the capture — build up the pressure first, then harvest.
About this position
These pieces come from starting position #322.
SP-322 · ThroneScout — A knight starts on the edge (a/h) and the king sits centrally on d or e; the mirror twin stays in this family too.
The king starts on e1, the rooks on c1 and g1, the queen on d1.
Castling ends where it always does: king to g1 and rook to f1 on the short side, king to c1 and rook to d1 on the long one.
A bishop starts in the corner on a1: it has a single diagonal, which the b-pawn unlocks, running out to h8.
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 343.
The engine's main line opens with e3.
Morozov Balance Index: 91 of 100 — class A — most balanced. Engine evaluation of the starting position: +13 centipawns for White (depth 47, 400 000 000 nodes).
Explore position #322Provenance
Mined from the project's engine self-play games.
Pack 015 · SP-322
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