Chess notation cheat-sheet (for new readers)
Pieces: K king · Q queen · R rook · B bishop · N knight · (a pawn move has no letter)
Actions: x takes · + check · # mate · O-O short castles · O-O-O long castles · e8=Q pawn promotes to queen
Annotations: ! good move · !! brilliant · ? mistake · ?? blunder
Why a check the king must answer hands you a free tempo
A king that has lost its pawns or been dragged off its shelter cannot wave a check away. It has to move, block, or capture, and while it deals with that the defender gets no time to haul a piece back or trade off your attacker. That is the engine behind these positions. The right check is a move you play for free while the opponent answers a question they did not want.
So the search is simple to state and hard to do: find the checks that keep the king busy and keep it boxed in. A queen lands with check, the king steps up, a knight or rook arrives with another check, and the king climbs higher each move. The exposed king is the target because it turns ordinary moves into forcing ones. Give it a quiet move instead, let it tuck a piece in front, and the attack stalls.
Reading the line back to front before the first check leaves the board
The mistake in a king hunt is checking on instinct and hoping the next move shows up. These puzzles ask the opposite. You read the whole line, last move first, before you touch a piece.
Map the escape squares. Look at where the king can run and which of your pieces already cover those squares. A check that herds the king toward your rook is worth more than one that lets it slip back to safety.
Order your checks. Most king walks have one move order that works and several that fizzle. Picture the king on each forced square and ask what checks it again from there.
Know the cash-out. The line ends in mate, in winning material, or in a perpetual when no mate exists. Decide which one you are aiming at so you stop at the right move.
Weighing the sac that tears the last pawn off the king
Plenty of these positions open with an offer: a bishop crashing on h7, a piece that drags the king out, an exchange thrown onto the long diagonal. The test is whether the king has somewhere to hide once the smoke clears. Count the attackers you can throw at its new home and the defenders that can rush back, and trace the king's walk to the square it ends on. If your pieces arrive first and it lands on an open square, the sac holds. If it slides into a fresh nest of its own pieces, you have handed over material for a king that simply castled by hand.
Running that count fast is the habit I keep sharpening on this trainer, and it is what the drill rewards. The positions come from real games, with a rating slider from about 400 to 2400 that keeps your solve rate near three in four. When a line goes dark you get three free hints, the motif first, then the piece, then the move. Many of these overlap with the kingside-attack set, where the same h7 and g7 offers turn up against a king that has not yet been forced into the open.