user16626: According to Wikipedia, "any chess piece except the king may be sacrificed". However, I am wondering,if in some rare situations, whether endangering the king can also be a good strategy. Here is what I mean.
In a position, I make a move after which my opponent has a checkmate in one. But this checkmate is very counterintuitive and is difficult to find, especially if my opponent is not so strong and/or they are in time trouble. If they miss this checkmate, my position is actually better.
Are there any examples of the above-mentioned scenario? Can endangering the king be a good idea occasionally, or should it always be avoided?

user10380: Further to existing answers, another sort of checkmate in 1 that might be tricky to spot is checkmate by discovered check.

user15223: A maxim in chess is not to play a move while thinking "I hope he doesn't see it". This doesn't mean that your opponent will always spot the threat - and if they don't then congratulations on the easy win - but the point is that if opponent spots the threat, your move should still improve your position in some way.
Example:
[FEN ""]
1. e4 e5 2. Nf3 Nc6 3. Bc4 Nd4? 4. Nxe5?? Qg5 {Black wins material thanks to the dual threats of 5...Qxe5 and 5...Qxg2 6. Rf1 Qxe4+ 7. Be2 Nf3# if White rescues the knight with 5. Nxf7.}

So 3...Nd4 wins material if opponent doesn't see the threat. It's still not a good move however, because if it's parried (4. Nxd4 or 4. O-O) White gets a strong advantage.
You are describing something even worse than a simple bad move, since the consequence of opponent seeing it is you lose the game. Now if you are going to lose the game anyway, then it's a reasonable gambit to try, but in all other situations you should never intentionally make a move that can lose your the game if your opponent spots the refutation.

user7186: Yes!
It is absolutely a valid strategy in online play with fast time controls. Here (youtube link) is an example in online play between two international masters:
[FEN "K/8/1R/8/8/5k/8/4qqqq w - - 0 1"]

1. Ka7 Qxb6 2. Ka8 Qef2?

After Qxb6, White has two moves, to take the queen which is mate in 3, or move to the corner which is mate in one. In the game, White played into the corner, which black did not expect, leading black to blunder stalemate before realizing what had happened.

user10380: What checkmate in 1 might be tricky to spot? One possibility: promoting a pawn to a knight. This might work better online than over the board: the software your opponent uses might make it easier to promote to queen than to another piece, and indeed some players have "auto-queen" turned on.

user11144: Whereas "sacrifice" is a bad word, as already was pointed out ("endangering" maybe), from the standpoint of game theory this strategy may be completely rational...if the players are fallible.
I abstract your example a bit. Assume the position is already at a -3 value with objective play value, i.e. it is lost. You have moves A and B. All opponent moves on A give a -3 position. On B the opponent can mate immediately (-infinity) or blunder away (0). The minimax value thus is -3, and a computer plays A since -infinity<-3. With "hope chess" you play B - you don't have to lose anything since you will "normally" lose anyway. But since you wanted a position:
[FEN "2k5/2b5/N1KPN3/8/7B/8/8/8 b - - 0 1"]
[startflipped ""]

Black to move. "Best" is 1...Bxd6, and White only has to mate with BNN, not that hard. But why not shorten the torture by 1...Bd8? Maybe White is a patzer and triumphantly captures the B...stalemate.

16626: <p>According to <a href="https://en.wikipedia.org/wiki/Sacrifice_(chess)" rel="nofollow noreferrer">Wikipedia</a>, &quot;any chess piece except the king may be sacrificed&quot;. However, I am wondering,if in some rare situations, whether endangering the king can also be a good strategy. Here is what I mean.</p>
<p>In a position, I make a move after which my opponent has a checkmate in one. But this checkmate is very counterintuitive and is difficult to find, especially if my opponent is not so strong and/or they are in time trouble. If they miss this checkmate, my position is actually better.</p>
<p>Are there any examples of the above-mentioned scenario? Can endangering the king be a good idea occasionally, or should it always be avoided?</p>
 10380: <p>Further to existing answers, another sort of checkmate in 1 that might be tricky to spot is checkmate by discovered check.</p>
 15223: <p>A maxim in chess is not to play a move while thinking &quot;I hope he doesn't see it&quot;. This doesn't mean that your opponent will always spot the threat - and if they don't then congratulations on the easy win - but the point is that if opponent spots the threat, your move should still improve your position in some way.</p>
<p>Example:</p>
<pre><code>[FEN &quot;&quot;]
1. e4 e5 2. Nf3 Nc6 3. Bc4 Nd4? 4. Nxe5?? Qg5 {Black wins material thanks to the dual threats of 5...Qxe5 and 5...Qxg2 6. Rf1 Qxe4+ 7. Be2 Nf3# if White rescues the knight with 5. Nxf7.}
</code></pre>
<p>So 3...Nd4 wins material if opponent doesn't see the threat. It's still not a good move however, because if it's parried (4. Nxd4 or 4. O-O) White gets a strong advantage.</p>
<p>You are describing something even worse than a simple bad move, since the consequence of opponent seeing it is you lose the game. Now if you are going to lose the game anyway, then it's a reasonable gambit to try, but in all other situations you should never intentionally make a move that can lose your the game if your opponent spots the refutation.</p>
 7186: <h2>Yes!</h2>
<p>It is absolutely a valid strategy in online play with fast time controls. Here <a href="https://youtu.be/YB_LLivPlY8?t=250" rel="nofollow noreferrer">(youtube link)</a> is an example in online play between two international masters:</p>
<pre><code>[FEN &quot;K/8/1R/8/8/5k/8/4qqqq w - - 0 1&quot;]

1. Ka7 Qxb6 2. Ka8 Qef2?
</code></pre>
<p>After Qxb6, White has two moves, to take the queen which is mate in 3, or move to the corner which is mate in one. In the game, White played into the corner, which black did not expect, leading black to blunder stalemate before realizing what had happened.</p>
 10380: <p>What checkmate in 1 might be tricky to spot? One possibility: promoting a pawn to a knight. This might work better online than over the board: the software your opponent uses might make it easier to promote to queen than to another piece, and indeed some players have &quot;auto-queen&quot; turned on.</p>
 11144: <p>Whereas &quot;sacrifice&quot; is a bad word, as already was pointed out (&quot;endangering&quot; maybe), from the standpoint of game theory this strategy may be completely rational...if the players are fallible.</p>
<p>I abstract your example a bit. Assume the position is already at a -3 value with objective play value, i.e. it is lost. You have moves A and B. All opponent moves on A give a -3 position. On B the opponent can mate immediately (-infinity) or blunder away (0). The minimax value thus is -3, and a computer plays A since -infinity&lt;-3. With &quot;hope chess&quot; you play B - you don't have to lose anything since you will &quot;normally&quot; lose anyway. But since you wanted a position:</p>
<pre><code>[FEN &quot;2k5/2b5/N1KPN3/8/7B/8/8/8 b - - 0 1&quot;]
[startflipped &quot;&quot;]
</code></pre>
<p>Black to move. &quot;Best&quot; is 1...Bxd6, and White only has to mate with BNN, not that hard. But why not shorten the torture by 1...Bd8? Maybe White is a patzer and triumphantly captures the B...stalemate.</p>
