Winning blow: queen to a7 (a2·2)
c9-28398naming 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.
Winning tactic: there is a move that gains a decisive advantage — find it.
Difficulty 1700 ShuffleRating — for advanced tacticians.
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 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 g1, queen a2, rook b1, bishop a1 e4, pawn d2 g2 h2 c4 f4 e5.
Black: king e8, queen c8, rook h8, bishop a8 f8, pawn c5 g5 e6 a7 d7 f7 g7.
11 white and 12 black pieces are on the board; the puzzle position arises after move 17.
The position in numbers
Black are ahead by 1 points of material (26 against 27; 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 e8.
It is White to move on move 17, with 43 legal replies to weigh — only the line that keeps the advantage solves the puzzle.
White keeps 6 pawns, Black 7. Files fully open (no pawns of either colour): b — natural highways for the rooks and queen. Half-open for White: a.
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
17. Qxa7 Bxe4 18. Rb8 Qxb8 19. Qxb8+ Ke7 20. fxg5
Why it works
- Great move! queen to a7 keeps the pressure (+4.3).
- rook to b8 develops smoothly.
- Strong! queen to b8 is the sharp choice (+4.6).
- Best move. pawn to g5 is exactly what the engine plays (+4.8).
- You win a piece — the queen.
- If instead Bxe4, then Rb8 and you stay on top.
Move by move
- 17. Qxa7 — queen to a7 (capture)
- Bxe4 — bishop to e4 (capture)
- 18. Rb8 — rook to b8
- Qxb8 — queen to b8 (capture)
- 19. Qxb8+ — queen to b8 (capture) with check
- Ke7 — king to e7
- 20. fxg5 — pawn to g5 (capture)
Types in this puzzle
Sacrifice attack
Give up material to unleash a decisive attack.
A sacrificial attack gives up material on purpose to rip the king's shelter open and launch a decisive assault. The sac is sound when you get concrete assets in return: open lines to the king, tempi, pieces ready to pour in. The signs: a poorly sheltered king, your forces aimed at its home, defenders stranded far away. The iron rule is to calculate, not hope — once the material is gone, there is no way back.
Counter-strike
Don't defend — answer the threat with a bigger one.
The counter-strike: instead of defending against the threat, you answer with a bigger threat of your own. While your opponent grabs a pawn, you deliver mate — the arithmetic favors you. Look for a counter when direct defenses fail: do you have a check, an attack on the queen, a mating threat? The beginner's error is meeting every threat with a reflexive defense without checking the counterattacking resources first.
About this position
These pieces come from starting position #690.
SP-690 · ThroneGuard — King on a central file (d/e) with both knights on inner files — the classic-type setup.
The king starts on d1, the rooks on b1 and h1, the queen on c1.
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, f2.
The setup belongs to the ThroneGuard family; read right to left it becomes position 455.
The engine's main line opens with b4.
Morozov Balance Index: 94 of 100 — class A — most balanced. Engine evaluation of the starting position: +10 centipawns for White (depth 43, 400 000 000 nodes).
Explore position #690Provenance
Mined from the project's engine self-play games.
Pack 013 · SP-690
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