11
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After this puzzle has been solved, it is time to offer our clever solvers another Loser Chess game to reconstruct...


Do you remember that I often pay a visit to my friends Fabi and Mag on evenings ? Most often I find them bending over a chessboard. They love to play chess, but once in a while, they experiment with Loser Chess instead of the more mundane game. It was the case last night, and when I arrived Mag, sitting in front of the white pieces, was thinking in this position:

enter image description here

Usually Loser Chess involves lots of early captures, but here only one bishop was missing, so I was surprised when Fabi told me that he had already played his 18th move !

Can you help me understand how they reached that position ?


In Loser chess, the rules are the same as in classical chess but for the following points:

  • The king behaves just as any normal piece and can be captured. There is no check, no checkmate, and the king being under attack is not an issue if you want to castle.

  • If you can capture a piece, you have to capture it.

  • If you can capture several pieces, you can choose to take whichever of them.

  • In case of a promotion, a pawn can be changed into a second king.

  • You win if and only if you are stalemated, i.e. either when your opponent has taken all your pieces or when none of your remaining pieces can move.

(as a consequence, Mag's next move is forced: he will play 19.Bxh6, and Fabi will have to choose between 19...Rxh6 and 19...Nxh6)


This problem was created by Michel Caillaud in 2006.


Hint 1

The first (easy) step is to find out on which square the single capture has happened.

Hint 2

When this problem was first published, it came with the header "Le refuge secret", which translates to "the secret hiding place".

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My solution (found shortly after instantsoup)

1. d3 Nf6 2. Kd2 g5 3. Ke3 Bh6 4. Bd2 Rf8
5. Bc3 Ng8 6. Bh8 g4 7. Kd4 Bg5 8. Na3 h6
9. Qb1 Bd2 10. Qd1 Bb4 11. Nb1 Ba3 12. bxa3 Nc6
13. Kc3 d5 14. Kb3 Be6 15. Bb2 Qd7 16. c3 Nf6
17. a4 Rh8 18. Bc1 Ng8

https://lichess.org/JXJKPMxz


The game in an animated gif:

enter image description here

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  • $\begingroup$ Very impressive. I thought this one was a bit easier, but I didn't expect the solution to be found that fast. I think the experience of solving the previous proof game helped you to be most effective in this one. $\endgroup$ – Evargalo Oct 31 '18 at 7:34
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    $\begingroup$ @Evargalo - spot on. If you'll remember, in your puzzle, my very first solution was to use the knight to prevent the queen from being able to take black's light-squared bishop after it captures the rook on f1! That's basically the same idea here. $\endgroup$ – Parseltongue Oct 31 '18 at 15:18
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I think this is it: https://lichess.org/ftOCzIHy

1. d3 Nf6 2. Kd2 g5 3. Ke3 Bh6 4. Bd2 Rf8 5. Bc3 Ng8 6. Bh8 g4+ 7. Kd4 Bg5 8. Na3 h6 9. Qb1 Bd2 10. Qd1 Bb4 11. Nb1 Ba3 12. bxa3 Nc6+ 13. Kc3 d5 14. Kb3 Be6 15. Bb2 Qd7 16. Bc1 Nf6 17. c3 Rh8 18. a4 Ng8


Well here goes another week!

First step, finding out the capture:

bxa3, which means Ba3 had to happen.

Absolutely required moves for white (4): bxa3, a4, c3, d3
Absolutely required moves for black (2): Ba3, h6

Time to clean out the black squares for the bishop!

Moves for white to setup black bishop moving (9):
d3, Kd2, [Kc3 | Ke3], [Kd4 | Ke4], Ke5, Bf4, Bg3, Na3, Qb1

Moves for white to reach ending position (10):
bxa3, Qd1, Nb1, Bf4, Bc1, a3, c3, King 3 moves

EDIT: I can't cut that down any more and it's at 19. I think the king moves too much. There also isn't a secret hiding place.

EDIT: I found the secret hiding place!

The white bishop hides in h8!

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    $\begingroup$ Great work! It's a real bummer, since my very first solution was 21 moves and used Bh8 as the main idea. Wish I had notifications set up! Next one needs to be harder! $\endgroup$ – Parseltongue Oct 30 '18 at 23:40
  • $\begingroup$ This one seemed to have fewer variations. $\endgroup$ – Instantsoup Oct 30 '18 at 23:41
  • $\begingroup$ Agreed. Last one was far deeper. We knew d2 had to be cleared and there were only two hiding places on the board for white's bishop. At least we didn't lose a week in productivity! $\endgroup$ – Parseltongue Oct 30 '18 at 23:43
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    $\begingroup$ Isn't 17. c3 illegal since white has 17. Bxh6? $\endgroup$ – jafe Oct 31 '18 at 0:34
  • $\begingroup$ It is, you're right. I was a little bit off. $\endgroup$ – Instantsoup Oct 31 '18 at 15:11
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I think white has to clear the d2 square for the black bishop somehow. We can get there in 19 moves...

1. d3 Na6
2. Kd2 g5
3. Ke3 g4
4. Ke4 Nb8
5. Ke5 Na6
6. Bf4 Nb8
7. Bg3 Na6
8. Na3 Bh6
9. Qb1 Bd2
10. Qd1 Bb4
11. Nb1 Ba3
12. bxa3 Nb8
13. Bf4 Na6
14. Bc1 Nb8
15. Kd4 Nc6
16. Kc3 d5
17. Kb3 Be6
18. a4 Qd7
19. c3 h6

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  • $\begingroup$ Move 17. Bf6, I think you mean Be6 $\endgroup$ – Parseltongue Oct 30 '18 at 23:26

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