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From the *starting position of a chessboard, you need to move the pieces to end up with 18 Queens following the chess rules at all times (this includes white moves first). The solution is the series of moves (not the final position, as there are plenty).

Having other remaining pieces is possible and allowed (e.g. a remaining bishop + the 18 queens and 2 kings).

* starting position FEN: rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - 0 1

see also the orignial question on chess stackexchange

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  • $\begingroup$ What is the question? $\endgroup$
    – skv
    Commented Nov 4, 2014 at 6:24
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    $\begingroup$ I understand your feeling, but would you agree that this is a pure chess question and not a Puzzle. $\endgroup$
    – skv
    Commented Nov 4, 2014 at 6:45
  • $\begingroup$ don't agree, I might came with a solution a grand master might not be able to, I am just an average player. But having the requisite of knowing the chess rules in order to solve the puzzle is kind of harsh I agree, thats why I admit earlier this might not fit too well in this site $\endgroup$
    – ajax333221
    Commented Nov 4, 2014 at 6:46
  • $\begingroup$ I have deleted my comment if thats what offended you, I apologise, but I still feel this is Chess SE question $\endgroup$
    – skv
    Commented Nov 4, 2014 at 6:47
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    $\begingroup$ There's crossposting though - that's considered against rules $\endgroup$
    – d'alar'cop
    Commented Nov 5, 2014 at 11:05

2 Answers 2

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This is known as the "18 Queens Problem". I know of this well-known solution by Friedrich Burchard & Friedrich Hariu, published in the German magazine feenschach issue #33 in 1976 on page 22. It can be viewed and downloaded as a PDF (the challenge was issued in #31.

(1976) in 96 Half-moves. I can't make a claim to its optimality, but by looking at it and seeing that no better can be found, I'd say it may well be optimal.

  1. e4 f5 2. e5 Nf6 3. exf6 e5 4. g4 e4 5. Ne2 e3 6. Ng3 e2 7. h4 f4 8. h5 fxg3 9. h6 g5 10. Rh4 gxh4 11. g5 g2 12. g6 Bg7 13. hxg7 g1=Q 14. f4 h3 15. f5 h2 16. b4 a5 17. b5 a4 18. b6 a3 19. Bb2 Ra7 20. bxa7 axb2 21. a4 b5 22. a5 b4 23. a6 b3 24. c4 h1=Q 25. c5 h5 26. c6 Bb7 27. cxb7 c5 28. d4 c4 29. d5 Nc6 30. dxc6 c3 31. c7 c2 32. c8=Q c1=Q 33. b8=Q Qc7 34. a8=Q d5 35. a7 d4 36. Nc3 dxc3 37. Qa6 c2 38. Qa8b7 c1=Q 39. a8=Q Qd5 40. gxh8=Q+ Kd7 41. g7 bxa1=Q 42. g8=Q b2 43. f7 b1=Q 44. f8=Q h4 45. f6 h3 46. f7 h2 47. Qfa3 h1=Q 48. f8=Q exf1=Q+

You can play it out on apronus.com.

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    $\begingroup$ It takes 80 moves to move pawns forward. Obviously they cannot capture the king and queen so there are only 6 promotion fields left on each side. Basically this means it takes at least 4 halfmoves to clear additional promotion fields. Then there are 8 pawn rows that block eachother, each conflict will need to be solved by capturing at least 1 piece that is not on it's starting position, hence we need another 8 half moves. Now we already have a lower bound of 92 and there are still some issues to solve. As such 96 is probably optimal. $\endgroup$
    – Dennis Jaheruddin
    Commented Jan 23, 2015 at 15:33
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My score is 104 half-moves:

1.a4 b5 2.a5 b4 3.a6 Bb7 4.axb7 h5 5.bxa8=Q h4 6.g4 h3 7.Bg2 hxg2 8.Ra3 bxa3 9.b4 gxh1=Q 10.e4 a2 11.b5 a1=Q 12.b6 a5 13.b7 d5 14.c4 Nd7 15.c5 Nb6 16.cxb6 Rh5 17.gxh5 g5 18.h6 g4 19.h7 g3 20.h4 a4 21.h5 a3 22.h8=Q a2 23.h6 axb1=Q 24.h7 g2 25.Bb2 d4 26.Bc3 dxc3 27.d4 c2 28.b8=Q c1=Q 29.b7 e5 30.Ke2 c5 31.Nf3 c4 32.Qba7 Bc5 33.dxc5 c3 34.Nd4 exd4 35.f4 Kd7 36.e5 Ne7 37.f5 Ng6 38.fxg6 f5 39.g7 f4 40.g8=Q Qca3 41.c6+ Ke7 42.e6 Kd6 43.c7 c2 44.Qhg7 c1=Q 45.Qc2 d3+ 46.Kf3 d2+ 47.Ke4 d1=Q 48.c8=Q f3 49.e7 f2 50.e8=Q f1=Q 51.h8=Q Qc7 52.b8=Q g1=Q+

You can view the game in here.

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