Answers.Body: <blockquote class="spoiler">
    <p> It's an "en passant" problem.<br>
   Black's last move had to have been <code>0..., e5</code>.  Then when white captures the pawn en passant with <code>1. dxe6 e.p.</code>, black is mated by the white bishop on b2 since the black f7 pawn is pinned by the white b7 rook and can't interpose to block the bishop.</p>
  </blockquote>
  
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Answers.CreationDate: 2020-05-05T18:28:34.620Z
Answers.LastActivityDate: 2020-05-05T18:39:40.783Z
Answers.LastEditDate: 2020-05-05T18:39:40.783Z
Answers.UserDisplayName: CConero
Answers.Body: <p>Black touched the white queen rook but moved their own rook from d8.  Therefore,
  they have to undo the rook move, putting that rook back on d8.  And capture the white
  rook with the Queen.  Then B x P is mate. Because the board is upside down.
  Well, okay, if the board is upside down, it wasn't White's Queen rook, but the King Rook.  NO matter.</p>
  
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Answers.CreationDate: 2021-01-17T10:07:38.687Z
Answers.Text: Welcome to Chess! I'm afraid that doesn't work; the pawn on e5 which you hope to capture with the bishop is also protected by the d6 pawn, not just by the rook.
Answers.UserDisplayName: Glorfindel
Answers.ContentLicense: CC BY-SA 4.0
Answers.CreationDate: 2023-12-31T05:23:02.357Z
Answers.Text: Though this doesn't work it seems an appropriate type of answer to the problem as stated.  It is an outside the box approach.
Answers.UserDisplayName: Ross Millikan
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Answers.LastEditDate: 2021-01-17T05:31:05.020Z
Answers.UserDisplayName: Andre bourbaki
Answers.Body: <p>Black's last move was 1.....e7-e5, &amp; so the mate in one is achieved with 2.de6 en passant (ep). Stockfish will have to do better. I have featured this study on my YouTube channel, plus a lot more. Happy solving! NB. I note in the 'spoiler' that it is of the opinion that Black had many alternatives to 1....e7-e5. Not so, because White's last move was evidently 1.Bb2+ (B at c1 to b2, as per my video on YouTube from 11 months back), requiring either the given reply or 1...f6 (2.Bf6# to finish). This proves my answer is not repeating others, but, on the contrary, identifying the correct sequence &amp; that no 'trick' or 'spoil' exists. To sum up &amp; leave no room for doubt (thus vindicating the composer),if the Black e-pawn were on e6 then 1...f6 would not be possible (f-pawn pinned by the Rook at b7, hence no alternative move at all), &amp; that e6-e5 would not enable White to deliver mate in one &amp; so e7-e5 is the only possible &amp; logical reply to 1.Bb2+ to bring into being a # in 1.</p>
  
Answers.ContentLicense: CC BY-SA 4.0
Answers.CreationDate: 2023-12-30T18:40:22.943Z
Answers.Text: Just repeating other answers isn't an answer
Answers.UserDisplayName: Brian Towers
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Answers.LastEditDate: 2023-12-31T06:33:08.783Z
Answers.UserDisplayName: Stephen Witherington
Answers.Body: <p>I checked with Stockfish and indeed there is no normal mate in one for White, and there isn't a mate in one for Black either. So this obviously a trick/joke problem.</p>
  
  <p>The trick is this: What last move of Black would allow a mate in one?</p>
  
  <p>Solution:</p>
  
  <blockquote class="spoiler">
    <p> The mate in one is “1. dxe6#” en passant! This move takes away the Black king's only flight square on h8, which is what stops any other attempts by White.</p>
  </blockquote>
  
  <p>Explanation:</p>
  
  <blockquote class="spoiler">
    <p> The joke is that it can't be proved that Black's last move was “0... e5”. The <a href="https://www.janko.at/Retros/Glossary/EnPassant.htm" rel="noreferrer">accepted convention</a> in chess problems is that an en passant capture is only allowed on the first move of the solution if it can be proved that the captured Black pawn made the double-step as Black's last move. It is obvious that Black has plenty of possible last moves other then e5, hence why this a trick problem.</p>
  </blockquote>
  
Answers.ContentLicense: CC BY-SA 4.0
Answers.CreationDate: 2020-05-01T01:15:28.783Z
Answers.LastActivityDate: 2020-05-10T12:38:32.027Z
Answers.LastEditDate: 2020-05-10T12:38:32.027Z
Answers.UserDisplayName: Rewan Demontay
Body: <blockquote>
    <p>I've received an (I would say impossible) <code>mate-in-one challenge</code> and I have already checked all movements, but couldn't solve it yet. It came from a trustable source and they say <em>you need to think outside the box</em>, so certainly there's a solution. Can someone help me to find it out?</p>
  </blockquote>
  
  <pre><code> [FEN "2q1rb2/pR3pkr/3p2pN/2nPp1QP/1nB1P1b1/6N1/PBP3P1/5RK1 w - - 0 1"]
  
  1. Qg6 Kh8 (1. Qf6 Kh6) (1. Qe5 Re5) (1. Be5 Re5) (1. Ngf5 Kh8) (1. Rff7 Kh8) 2. Qg8
  </code></pre>
  
  <p>White moves, and it is pretty close to win. <code>Qxg6, Qg8</code> could be a two-movement winning sequence. However, as said in the challenge statement, <strong>it is possible to be victorious in the very next movement</strong>, so I have been wondering how! </p>
  
  <h2>The original statement is:</h2>
  
  <blockquote>
    <p>Today's puzzle is one of the most trickiest chess problems you'll ever see. All you need is to think outside the box. White to move and mate in one! Yes, in one move. No, no extra pieces are appearing on the board likewise no removal. It's achieved with one unique valid movement, are you able to solve it?</p>
  </blockquote>
  
  <p>There's just 6 possible checks white can do (I mean, i just saw 6). All them are included in above board followed by how black escape from it.</p>
  
  <p>Can anyone find the solution?</p>
  
  <p>Also also also also, for honesty here, I googled the FEN to find the <a href="https://www.ecforum.org.uk/viewtopic.php?t=8908" rel="noreferrer">answer</a>.</p>
  
Comments.ContentLicense: CC BY-SA 4.0
Comments.CreationDate: 2020-05-01T04:06:45.480Z
Comments.Text: It went right to the point! Thanks for the help. I actually suggested some typo correction to the answer, look there
Comments.UserDisplayName: artu-hnrq
Comments.ContentLicense: CC BY-SA 4.0
Comments.CreationDate: 2020-05-01T13:12:49.617Z
Comments.Text: If the board would be upside down, Bxd4 would have been mate too, except for the black rook on d1. (Bxe5 and Re8 in the current orientation.)
Comments.UserDisplayName: Glorfindel
Comments.ContentLicense: CC BY-SA 4.0
Comments.CreationDate: 2020-05-01T16:02:57.377Z
Comments.Text: https://www.youtube.com/watch?v=v5d1YqwlDLA gives his explanation.  Another "out-of-box" answer is that this is bughouse/crazyhouse and the drop/complete the move of Bf6.
Comments.UserDisplayName: Mike Jones
Comments.ContentLicense: CC BY-SA 4.0
Comments.CreationDate: 2020-05-05T21:01:40.357Z
Comments.Text: Can you add the source for this puzzle? A redditor recently posted this, and said that it was in an online quiz.
Comments.UserDisplayName: Herb
Comments.ContentLicense: CC BY-SA 4.0
Comments.CreationDate: 2020-05-05T21:18:41.320Z
Comments.Text: It was on [fide_chess](https://www.instagram.com/p/B_b1cc_jLlc/?igshid=4kb3wdrfc54s) Instagram page
Comments.UserDisplayName: artu-hnrq
Tags: <analysis><checkmate><problems>
Title: Outside-the-box mate-in-one challenge
ThreadText: # Outside-the-box mate-in-one challenge
  
  (Asked by: username_0 on 2020-05-01)
  
  > I've received an (I would say impossible) `mate-in-one challenge` and I have already checked all movements, but couldn't solve it yet. It came from a trustable source and they say *you need to think outside the box*, so certainly there's a solution. Can someone help me to find it out?
  
  ```
   [FEN "2q1rb2/pR3pkr/3p2pN/2nPp1QP/1nB1P1b1/6N1/PBP3P1/5RK1 w - - 0 1"]
  
  1. Qg6 Kh8 (1. Qf6 Kh6) (1. Qe5 Re5) (1. Be5 Re5) (1. Ngf5 Kh8) (1. Rff7 Kh8) 2. Qg8
  
  ```
  
  White moves, and it is pretty close to win. `Qxg6, Qg8` could be a two-movement winning sequence. However, as said in the challenge statement, **it is possible to be victorious in the very next movement**, so I have been wondering how!
  
  ## The original statement is:
  
  > Today's puzzle is one of the most trickiest chess problems you'll ever see. All you need is to think outside the box. White to move and mate in one! Yes, in one move. No, no extra pieces are appearing on the board likewise no removal. It's achieved with one unique valid movement, are you able to solve it?
  
  There's just 6 possible checks white can do (I mean, i just saw 6). All them are included in above board followed by how black escape from it.
  
  Can anyone find the solution?
  
  Also also also also, for honesty here, I googled the FEN to find the [answer](https://www.ecforum.org.uk/viewtopic.php?t=8908).
  
  **Tags:** analysis, checkmate, problems
  
  > **Comments:**
  > **username_0**: It went right to the point! Thanks for the help. I actually suggested some typo correction to the answer, look there  
  > **username_1**: If the board would be upside down, Bxd4 would have been mate too, except for the black rook on d1. (Bxe5 and Re8 in the current orientation.)  
  > **username_2**: https://www.youtube.com/watch?v=v5d1YqwlDLA gives his explanation.  Another "out-of-box" answer is that this is bughouse/crazyhouse and the drop/complete the move of Bf6.  
  > **username_3**: Can you add the source for this puzzle? A redditor recently posted this, and said that it was in an online quiz.  
  > **username_0**: It was on [fide_chess](https://www.instagram.com/p/B_b1cc_jLlc/?igshid=4kb3wdrfc54s) Instagram page  
  
  ---
  
  ## 4 answers
  
  ### Answer by username_9 on 2020-05-01. Score: 18 | Accepted answer
  
  I checked with Stockfish and indeed there is no normal mate in one for White, and there isn't a mate in one for Black either. So this obviously a trick/joke problem.
  
  The trick is this: What last move of Black would allow a mate in one?
  
  Solution:
  
  > The mate in one is “1. dxe6#” en passant! This move takes away the Black king's only flight square on h8, which is what stops any other attempts by White.
  
  Explanation:
  
  > The joke is that it can't be proved that Black's last move was “0... e5”. The [accepted convention](https://www.janko.at/Retros/Glossary/EnPassant.htm) in chess problems is that an en passant capture is only allowed on the first move of the solution if it can be proved that the captured Black pawn made the double-step as Black's last move. It is obvious that Black has plenty of possible last moves other then e5, hence why this a trick problem.
  
  
  ---
  
  ### Answer by username_4 on 2020-05-05. Score: 4
  
  > It's an "en passant" problem.  
  > Black's last move had to have been `0..., e5`. Then when white captures the pawn en passant with `1. dxe6 e.p.`, black is mated by the white bishop on b2 since the black f7 pawn is pinned by the white b7 rook and can't interpose to block the bishop.
  
  
  ---
  
  ### Answer by username_5 on 2021-01-17. Score: 2
  
  Black touched the white queen rook but moved their own rook from d8. Therefore,
  they have to undo the rook move, putting that rook back on d8. And capture the white
  rook with the Queen. Then B x P is mate. Because the board is upside down.
  Well, okay, if the board is upside down, it wasn't White's Queen rook, but the King Rook. NO matter.
  
  > **Comments:**
  > **username_1**: Welcome to Chess! I'm afraid that doesn't work; the pawn on e5 which you hope to capture with the bishop is also protected by the d6 pawn, not just by the rook.  
  > **username_6**: Though this doesn't work it seems an appropriate type of answer to the problem as stated.  It is an outside the box approach.  
  
  ---
  
  ### Answer by username_7 on 2023-12-30. Score: 0
  
  Black's last move was 1.....e7-e5, & so the mate in one is achieved with 2.de6 en passant (ep). Stockfish will have to do better. I have featured this study on my YouTube channel, plus a lot more. Happy solving! NB. I note in the 'spoiler' that it is of the opinion that Black had many alternatives to 1....e7-e5. Not so, because White's last move was evidently 1.Bb2+ (B at c1 to b2, as per my video on YouTube from 11 months back), requiring either the given reply or 1...f6 (2.Bf6# to finish). This proves my answer is not repeating others, but, on the contrary, identifying the correct sequence & that no 'trick' or 'spoil' exists. To sum up & leave no room for doubt (thus vindicating the composer),if the Black e-pawn were on e6 then 1...f6 would not be possible (f-pawn pinned by the Rook at b7, hence no alternative move at all), & that e6-e5 would not enable White to deliver mate in one & so e7-e5 is the only possible & logical reply to 1.Bb2+ to bring into being a # in 1.
  
  > **Comments:**
  > **username_8**: Just repeating other answers isn't an answer  
  
  ---
  
  