Chess Puzzles — free mate in one trainer

Every position here is White to move with exactly one mate in one. Not one that is best, not one that wins material — one move that ends the game on the spot, and only one. Find it and you get a fresh position with an extra piece on the board. Miss it and you lose a life; three misses end the run and your score is the number you solved.

The positions are generated fresh and then verified: the game plays out every legal White move and counts how many deliver checkmate, and it only shows you the position if that count is exactly one. Nothing is drawn from a puzzle database, so you will not meet the same position twice, and there is never an ambiguous answer. It is free, needs no account and no download, and works the same on a phone as on a desktop.

How to play

• Tap one of your pieces (White, the light ones) to see where it can legally go.
• Tap a highlighted square to play the move. A dot is a quiet move; a ring is a capture.
• The move must be checkmate immediately. Any other legal move costs a life.
• Three misses end the run. Your score is how many you solved.
• Each puzzle you solve adds a piece, so the board gets busier and the mate gets harder to spot.

Where the mate actually hides

Mate in one is a search problem with a very small answer space, and beginners search it in the wrong order. The instinct is to look at your strongest piece and its most natural square. The reliable method is the opposite: list every move that gives check, then test only those. Checkmate is check plus no escape, so any move that is not a check cannot possibly be mate, and on a normal board that cuts a list of thirty-odd legal moves down to three or four candidates.

Then, for each check, ask the three escape questions in order: can the king move, can the check be blocked, can the checking piece be captured? A mate is a check where all three answers are no. Most misses come from forgetting the third one — a queen delivered to a square where it looks devastating but is defended by a modest pawn is the single most common wrong answer in this game.

The corollary is the hint at the top of the board: the mating move very often looks like a blunder. Sacrifices dominate mate-in-one puzzles precisely because a move that hangs your queen is the move your eye skips. If you have checked every safe check and found nothing, start checking the unsafe ones — and remember that a piece defended by your own rook or bishop from across the board is not hanging at all, however alarming it looks.

One practical note about this trainer specifically: because a position is only shown when the mate is unique, you never have to wonder whether a second answer exists. If you have found a mate, it is the mate. If you like this kind of forced-move thinking, Five in a Row and Four in a Row reward spotting the same sort of unanswerable threat.

More games

More board games against a real opponent: Five in a Row, Checkers, Reversi and Four in a Row. Or browse all games.