Answers.Body: <p><strong>41 Half moves, not a real game</strong></p>
  
  <p>The first possible capture is indeed on the third half-move. After that, a perfect game would be purely captures. By counting the moves which don't involve a capture, you can show how close to a perfect king v king you got. Giving check is bad, unless the opposing king can take a piece while moving out of check (unlikely, if none of the pieces are moved)</p>
  
  <p>The following is a game I created to challenge this puzzle, and it includes 11 half moves which do not take a piece. The other 30 half moves are all captures. My solution is one half move faster than the OP's proposed solution (42 half moves):</p>
  
  <pre><code>[FEN "rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - 0 1"]
  1. e4 d5 2. exd5 Qxd5 3. Qh5 Qxg2 4. Qxh7 Qxh2 5. Qxh8 Qxh1 6. Qxg8 Qxg1 7. Qxg7 Qg6 8. Qxf7+ Kd7 9. Qxf8 Qxc2 10. Qxc8+ Kd6 11. Qxb8 Qxb2 12. Qxa8 Qxa2 13. Qxa7 Qxa1 14. Qxb7 Qxb1 15. Qxc7+ Ke6 16. Qxe7+ Kxe7 17. f3 Qxc1+ 18. Kf2 Qxd2+ 19. Be2 Qxe2+ 20. Kg3 Qxf3+ 21. Kxf3
  </code></pre>
  
  <p><strong>Now in 36 half moves:</strong></p>
  
  <pre><code>[FEN "rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - 0 1"]
  1. c4 d5 2. cxd5 Qxd5 3. Qc2 Qxa2 4. Qxh7 Qxb2 5. Qxg7 Qxb1 6. Qxg8 Rxh2 7. Rxa7 Rxh1 8. Rxa8 Rxg1 9. Rxb8 Rxg2 10. Rxb7 Rxf2 11. Rxc7 Qxc1+ 12. Kxf2 Qxd2 13. Rxc8+ Kd7 14. Qxf7 Qxe2+ 15. Kg3 Qxf1 16. Qxf1 Kxc8 17. Qxf8+ Kd7 18. Qxe7+ Kxe7
  </code></pre>
  
  <p>By using the queens and rooks I was able to take pieces from either side of the King. When only using the queen, I had to move the queen across to the other side without giving check, so using rooks aswell removed this problem.</p>
  
Answers.ContentLicense: CC BY-SA 3.0
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Answers.Text: Do you think this is the lowest we could go?
Answers.UserDisplayName: ericw31415
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Answers.Text: @ericw31415 I'm not sure. Perhaps I could make it lower By involving the rooks...
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Answers.Text: well, my guess is 36 is pretty close. If every move captured a piece, it would be 30. It seems like if there was a better solution, it would be 35 or  maybe 34(though looking at solution doesn't seem like you can be more efficient), given how long it takes to activate pieces.
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Answers.UserDisplayName: Aric
Answers.Body: <p>Francois Labelle has studied this as part of the more challenging problem of finding a unique proof game which ends with KvK. <a href="http://www.wismuth.com" rel="nofollow noreferrer">Labelle's site</a> contains a wealth of computational <a href="http://www.wismuth.com/chess/chess.html" rel="nofollow noreferrer">chess results</a>, including <a href="http://www.wismuth.com/chess/problems-massacre.html" rel="nofollow noreferrer">massacre proof games</a>, u.e. proof game problems where nearly all the moves are captures.</p>
  <p>He found one proof game leading to KvK in 19.5 moves, and has certainly got all the (non-unique) 16.5 games. A minor point worth noting is that any solution cannot end with a capture of a minor piece, or a forced capture, because there would be a prior dead position.</p>
  <p>His Stratgems 58 article on unique bare king proof games is <a href="https://wismuth.com/chess/2kings.html" rel="nofollow noreferrer">on his site.</a> Here is the full solution, taken from the <a href="https://pdb.dieschwalbe.de/P1235533" rel="nofollow noreferrer">Die Schwalbe Chess Problem Database.</a></p>
  <p>1.c4 e5 2. Qb3 Qh4 3. Qxb7 Qxh2 4. Qxb8 Qxg1 5. Rxh7 Rxb8 6. Rxg7 Rxb2 7. Rxf7 Rxa2 8. Rxd7 Rxd2 9. Rxa7 Kxd7 10. Rxc7+ Kd6 11. Rxc8 Qxg2 12. Rxf8 Kc5 13. Rxg8 Rxg8 14. Bxg2 Rxg2 15. Nc3 Rxf2 16. Kxf2 Kxc4 17. Kf3 Kxc3 18. Bxd2+ Kxd2 19. Ke4 Kxe2 20. Kxe5</p>
  <pre><code>[Title &quot;François Labelle, P0330 StrateGems (58), 6/4/2012&quot;]
  [FEN &quot;&quot;]
  
  1. c4 e5 2. Qb3 Qh4 3. Qxb7 Qxh2 4. Qxb8 Qxg1 5. Rxh7 Rxb8 6. Rxg7 Rxb2 7. Rxf7 Rxa2 8. Rxd7 Rxd2 9. Rxa7 Kxd7 10. Rxc7+ Kd6 11. Rxc8 Qxg2 12. Rxf8 Kc5 13. Rxg8 Rxg8 14. Bxg2 Rxg2 15. Nc3 Rxf2 16. Kxf2 Kxc4 17. Kf3 Kxc3 18. Bxd2+ Kxd2 19. Ke4 Kxe2 20. Kxe5
  </code></pre>
  
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Answers.UserDisplayName: Laska
Answers.Body: <p>This is a famous task, originally tackled by Sam Loyd and only improved a century later.  See <a href="http://www.chessvariants.com/problems.dir/twokingstask.html" rel="noreferrer">http://www.chessvariants.com/problems.dir/twokingstask.html</a>, which gives the refinement by Ponzetto:</p>
  
  <pre><code>[FEN "rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - 0 1"]
  1.e4 d5 2.exd5 Qxd5 3.Bd3 Qxa2 4.Bxh7 Qxb1 5.Bxg8 Qxc2 6.Bxf7+ Kxf7 7.Rxa7 Qxc1 8.Rxb7 Rxh2 9.Rxb8 Rxg2 10.Qxc1 Rxg1+ 11.Rxg1 Rxb8 12.Qxc7 Rxb2 13.Qxc8 Rxd2 14.Qxf8+ Kxf8 15.Rxg7 Rxf2 16.Rxe7 Kxe7 17.Kxf2
  </code></pre>
  
  <p>For reference, here's the original Loyd solution:</p>
  
  <pre><code>[FEN "rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - 0 1"]
  1. c4 d5 2. cxd5 Qxd5 3. Qc2 Qxg2 4. Qxc7 Qxg1 5. Qxb7 Qxh2 6. Qxb8 Qe5 7. Qxc8+ Rxc8 8. Rxh7 Qxb2 9. Rxh8 Qxa2 10. Rxg8 Qxd2+ 11. Kxd2 Rxc1 12. Rxg7 Rxb1 13. Rxf7 Rxf1 14. Rxf8+ Kxf8 15. Rxa7 Rxf2 16. Rxe7 Rxe2+ 17. Kxe2 Kxe7
  </code></pre>
  
  <p>[ <strong>ETA:</strong> Incidentally, while the linked article leaves it as an open problem, it seems like it would be a very straightforward task to show that 16.5 is optimal; at least at first glance I don't see any lines that have captures by both sides on all four half-moves in moves 2 and 3, which would imply that some form of 'off move' along the lines of White's 3. Bd3 is a strict necessity within the first few moves. ]</p>
  
Answers.ContentLicense: CC BY-SA 3.0
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Answers.Text: I think this is optimal. I said in my post that 33 half-moves was optimal.
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Answers.UserDisplayName: Steven Stadnicki
Body: <p>What is the fastest possible game that ends in a King vs King endgame? Please post a game and tell me the number of half-moves you've achieved. By some simple logic, I can prove that this number is greater than 32 half-moves. There are 30 pieces to be captured, and the first capture can only be made on the 3rd half-move or later.</p>
  
  <p>An example of such a game could be this:</p>
  
  <pre><code>[FEN "rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - 0 1"]
  1. e4 d5 2. exd5 c6 3. dxc6 Qa5 4. cxb7 Qxa2
  5. bxa8=Q Qxa1 6. Qxa7 Qxb2 7. Qxb8 Qxb1 8. Qh5 Qxc2
  9. Qxh7 Qxc1+ 10. Ke2 Qxd2+ 11. Kf3 Qe1 12. Qxh8 Qxf1
  13. Qxg7 Qxg1 14. Qxg8 Qxh1 15. Qxf7+ Kd7 16. Qxf8 Qxh2
  17. Qxe7+ Kxe7 18. Qxc8 Qxg2+ 19. Ke2 Qxf2+ 20. Kxf2 Kd6
  21. Qd7+ Kxd7
  1/2-1/2
  </code></pre>
  
  <p>achieving the result in 42 half-moves.</p>
  
Comments.ContentLicense: CC BY-SA 3.0
Comments.CreationDate: 2017-09-30T23:25:50.663Z
Comments.Text: The site that came to my mind for such records is [Tim Krabbe's chess records](https://timkr.home.xs4all.nl/records/records.htm). He has many records there, but I could not find the exact question you have there.
Comments.UserDisplayName: TMM
Tags: <problems><records><mathematics>
Title: Fastest King vs King endgame
ThreadText: # Fastest King vs King endgame
  
  (Asked by: username_0 on 2017-08-08)
  
  What is the fastest possible game that ends in a King vs King endgame? Please post a game and tell me the number of half-moves you've achieved. By some simple logic, I can prove that this number is greater than 32 half-moves. There are 30 pieces to be captured, and the first capture can only be made on the 3rd half-move or later.
  
  An example of such a game could be this:
  
  ```
  [FEN "rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - 0 1"]
  1. e4 d5 2. exd5 c6 3. dxc6 Qa5 4. cxb7 Qxa2
  5. bxa8=Q Qxa1 6. Qxa7 Qxb2 7. Qxb8 Qxb1 8. Qh5 Qxc2
  9. Qxh7 Qxc1+ 10. Ke2 Qxd2+ 11. Kf3 Qe1 12. Qxh8 Qxf1
  13. Qxg7 Qxg1 14. Qxg8 Qxh1 15. Qxf7+ Kd7 16. Qxf8 Qxh2
  17. Qxe7+ Kxe7 18. Qxc8 Qxg2+ 19. Ke2 Qxf2+ 20. Kxf2 Kd6
  21. Qd7+ Kxd7
  1/2-1/2
  
  ```
  
  achieving the result in 42 half-moves.
  
  **Tags:** problems, records, mathematics
  
  > **Comments:**
  > **username_1**: The site that came to my mind for such records is [Tim Krabbe's chess records](https://timkr.home.xs4all.nl/records/records.htm). He has many records there, but I could not find the exact question you have there.  
  
  ---
  
  ## 3 answers
  
  ### Answer by username_5 on 2017-10-03. Score: 14 | Accepted answer
  
  This is a famous task, originally tackled by Sam Loyd and only improved a century later. See <http://www.chessvariants.com/problems.dir/twokingstask.html>, which gives the refinement by Ponzetto:
  
  ```
  [FEN "rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - 0 1"]
  1.e4 d5 2.exd5 Qxd5 3.Bd3 Qxa2 4.Bxh7 Qxb1 5.Bxg8 Qxc2 6.Bxf7+ Kxf7 7.Rxa7 Qxc1 8.Rxb7 Rxh2 9.Rxb8 Rxg2 10.Qxc1 Rxg1+ 11.Rxg1 Rxb8 12.Qxc7 Rxb2 13.Qxc8 Rxd2 14.Qxf8+ Kxf8 15.Rxg7 Rxf2 16.Rxe7 Kxe7 17.Kxf2
  
  ```
  
  For reference, here's the original Loyd solution:
  
  ```
  [FEN "rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - 0 1"]
  1. c4 d5 2. cxd5 Qxd5 3. Qc2 Qxg2 4. Qxc7 Qxg1 5. Qxb7 Qxh2 6. Qxb8 Qe5 7. Qxc8+ Rxc8 8. Rxh7 Qxb2 9. Rxh8 Qxa2 10. Rxg8 Qxd2+ 11. Kxd2 Rxc1 12. Rxg7 Rxb1 13. Rxf7 Rxf1 14. Rxf8+ Kxf8 15. Rxa7 Rxf2 16. Rxe7 Rxe2+ 17. Kxe2 Kxe7
  
  ```
  
  [ **ETA:** Incidentally, while the linked article leaves it as an open problem, it seems like it would be a very straightforward task to show that 16.5 is optimal; at least at first glance I don't see any lines that have captures by both sides on all four half-moves in moves 2 and 3, which would imply that some form of 'off move' along the lines of White's 3. Bd3 is a strict necessity within the first few moves. ]
  
  > **Comments:**
  > **username_0**: I think this is optimal. I said in my post that 33 half-moves was optimal.  
  
  ---
  
  ### Answer by username_2 on 2017-08-09. Score: 9
  
  **41 Half moves, not a real game**
  
  The first possible capture is indeed on the third half-move. After that, a perfect game would be purely captures. By counting the moves which don't involve a capture, you can show how close to a perfect king v king you got. Giving check is bad, unless the opposing king can take a piece while moving out of check (unlikely, if none of the pieces are moved)
  
  The following is a game I created to challenge this puzzle, and it includes 11 half moves which do not take a piece. The other 30 half moves are all captures. My solution is one half move faster than the OP's proposed solution (42 half moves):
  
  ```
  [FEN "rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - 0 1"]
  1. e4 d5 2. exd5 Qxd5 3. Qh5 Qxg2 4. Qxh7 Qxh2 5. Qxh8 Qxh1 6. Qxg8 Qxg1 7. Qxg7 Qg6 8. Qxf7+ Kd7 9. Qxf8 Qxc2 10. Qxc8+ Kd6 11. Qxb8 Qxb2 12. Qxa8 Qxa2 13. Qxa7 Qxa1 14. Qxb7 Qxb1 15. Qxc7+ Ke6 16. Qxe7+ Kxe7 17. f3 Qxc1+ 18. Kf2 Qxd2+ 19. Be2 Qxe2+ 20. Kg3 Qxf3+ 21. Kxf3
  
  ```
  
  **Now in 36 half moves:**
  
  ```
  [FEN "rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - 0 1"]
  1. c4 d5 2. cxd5 Qxd5 3. Qc2 Qxa2 4. Qxh7 Qxb2 5. Qxg7 Qxb1 6. Qxg8 Rxh2 7. Rxa7 Rxh1 8. Rxa8 Rxg1 9. Rxb8 Rxg2 10. Rxb7 Rxf2 11. Rxc7 Qxc1+ 12. Kxf2 Qxd2 13. Rxc8+ Kd7 14. Qxf7 Qxe2+ 15. Kg3 Qxf1 16. Qxf1 Kxc8 17. Qxf8+ Kd7 18. Qxe7+ Kxe7
  
  ```
  
  By using the queens and rooks I was able to take pieces from either side of the King. When only using the queen, I had to move the queen across to the other side without giving check, so using rooks aswell removed this problem.
  
  > **Comments:**
  > **username_0**: Do you think this is the lowest we could go?  
  > **username_2**: @username_0 I'm not sure. Perhaps I could make it lower By involving the rooks...  
  > **username_3**: well, my guess is 36 is pretty close. If every move captured a piece, it would be 30. It seems like if there was a better solution, it would be 35 or  maybe 34(though looking at solution doesn't seem like you can be more efficient), given how long it takes to activate pieces.  
  
  ---
  
  ### Answer by username_4 on 2017-10-09. Score: 4
  
  Francois Labelle has studied this as part of the more challenging problem of finding a unique proof game which ends with KvK. [Labelle's site](http://www.wismuth.com) contains a wealth of computational [chess results](http://www.wismuth.com/chess/chess.html), including [massacre proof games](http://www.wismuth.com/chess/problems-massacre.html), u.e. proof game problems where nearly all the moves are captures.
  
  He found one proof game leading to KvK in 19.5 moves, and has certainly got all the (non-unique) 16.5 games. A minor point worth noting is that any solution cannot end with a capture of a minor piece, or a forced capture, because there would be a prior dead position.
  
  His Stratgems 58 article on unique bare king proof games is [on his site.](https://wismuth.com/chess/2kings.html) Here is the full solution, taken from the [Die Schwalbe Chess Problem Database.](https://pdb.dieschwalbe.de/P1235533)
  
  1.c4 e5 2. Qb3 Qh4 3. Qxb7 Qxh2 4. Qxb8 Qxg1 5. Rxh7 Rxb8 6. Rxg7 Rxb2 7. Rxf7 Rxa2 8. Rxd7 Rxd2 9. Rxa7 Kxd7 10. Rxc7+ Kd6 11. Rxc8 Qxg2 12. Rxf8 Kc5 13. Rxg8 Rxg8 14. Bxg2 Rxg2 15. Nc3 Rxf2 16. Kxf2 Kxc4 17. Kf3 Kxc3 18. Bxd2+ Kxd2 19. Ke4 Kxe2 20. Kxe5
  
  ```
  [Title "François Labelle, P0330 StrateGems (58), 6/4/2012"]
  [FEN ""]
  
  1. c4 e5 2. Qb3 Qh4 3. Qxb7 Qxh2 4. Qxb8 Qxg1 5. Rxh7 Rxb8 6. Rxg7 Rxb2 7. Rxf7 Rxa2 8. Rxd7 Rxd2 9. Rxa7 Kxd7 10. Rxc7+ Kd6 11. Rxc8 Qxg2 12. Rxf8 Kc5 13. Rxg8 Rxg8 14. Bxg2 Rxg2 15. Nc3 Rxf2 16. Kxf2 Kxc4 17. Kf3 Kxc3 18. Bxd2+ Kxd2 19. Ke4 Kxe2 20. Kxe5
  
  ```
  
  
  ---
  
  