Blunder Watch

Click on the lightbulb twice to see White's first move followed by the blunder. Can you find White's Queen sacrifice?

Click on the lightbulb twice to see Black's first move followed by the blunder.

Click on the lightbulb twice to see Black's first move followed by the blunder.

Great work, great effort!

You know the deal. Two lightbulb clicks to see Black's move, watch White blunder, and capitalize.

Nice puzzle. Instead of the blunder move, White should have castled king-side first.

Click the lightbulb twice to see Black's first move followed by the blunder.

Click the lightbulb twice to see Black's first move followed by the blunder. 

Click the lightbulb twice to see White's first move followed by the blunder. Find Mate.

Jon Ludvig Hammer vs. Magnus Carlsen
Chess.com: Live Chess: 2023.01.05

Nice! The best way to end the game.

Agree. Carlsen could have extended the game by blocking the h-Rook with his Bishop instead of blocking with the Knight. Then checking the White King with his Knight. But, this checkmate solution is stunning.

Click the lightbulb twice to see Black's first move followed by the blunder. Find Mate in 11 moves. The reason for so many moves is that you have to manoeuvre the White King until it's trapped against one of the sides of the board.

This puzzle doesn't necessarily end in mate if White makes the right moves.

Are you assuming that both Black and White will play with 100% accuracy in puzzles?

Yes, that's how puzzles work.

I don't understand the logic of this. I thought the purpose of a puzzle was for the solver to find the best possible move in response to whatever move the opponent provides. The solution of a puzzle usually has one side winning or gaining an advantage over the other side. That doesn't indicate both sides are playing with 100% accuracy unless the loser's moves are all forced and you count a forced move as 100% optimal.

Yes, you have to find the moves that give you an advantage no matter what your opponent plays. That includes the scenario where they happen to play with 100% accuracy. It doesn't matter if they do that or not; you just need to be winning in all lines.

There are chess.com fork puzzles where one side blunders and sets up a fork opportunity. The solver still has to see that fork to make a 100% accurate move to solve the puzzle. In puzzle #134 above, the blunder is not actually a blunder. That White pawn was deliberately promoted and sacked to deflect Black's Rook away to allow White's next move Qd7 to threaten Mate-in-one. Perhaps White could have won had Black not found that Brilliant move Rxf4+. The point is that I wanted to create a puzzle that included that Brilliant move and see if Black could continue the line all the way to checkmate. To make that happen I gave White a Mistake move. In real play, a game ending in Mate is usually the result of one side making more errors than the opponent. Where I have come unstuck with some of my puzzles is when I add a Best move which has a viable alternative Best move. Such a move exists in the above puzzle.  On move #5 Black could have played the equally valid 5.... Qh3+ with an x-ray through the White King and Queen and captured the White Queen on the next move. Sorry about that. Unfortunately, that line doesn't work as a Mating puzzle as it presents too many possible solutions. So, I concede that my puzzle is not perfect. But, if the solver gets most moves right then they should be well proud despite the minor imperfection of the puzzle.

As far as I analyzed, it appears that black does win in all lines (after the "blunder") so that would not be an issue. The failure of the puzzle is that the author also instructs the solver "to find the (presumably quick) mate". That however is impossible if white refuses to advance his king to f5. It's not a decent checkmate problem.

That's a good point. After the blunder, it took 9 moves to find Mate. In that circumstance, when Mate is still many moves away, should the author specify something like "Find Mate in 9 moves"? Otherwise, the puzzle just looks like Black chasing the White King around with checks without a recognizable plan to effect the checkmate.