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


closed as off-topic by skv, Joe, mdc32, Rob Watts, Psychemaster Nov 11 '14 at 21:19

  • This question does not appear to be about creation and solving of puzzles, within the scope defined in the help center.
If this question can be reworded to fit the rules in the help center, please edit the question.

  • $\begingroup$ What is the question? $\endgroup$ – skv Nov 4 '14 at 6:24
  • 3
    $\begingroup$ I understand your feeling, but would you agree that this is a pure chess question and not a Puzzle. $\endgroup$ – skv Nov 4 '14 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 Nov 4 '14 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 Nov 4 '14 at 6:47
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    $\begingroup$ There's crossposting though - that's considered against rules $\endgroup$ – d'alar'cop Nov 5 '14 at 11:05

This is known as the "18-Queens Problem". I found this well-known solution by Friedrich Burchard & Friedrich Hariuc (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 Qcc7 34.a8=Q d5 35.a7 d4
36.Nc3 dxc3 37.Qa6 c2 38.Qa8b7 c1=Q 39.a8=Q Qhd5 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+

I used the same PGN viewer as OP for consistency.

  • $\begingroup$ Why are you giving credit? Is this a known problem and this is a known solution? Is this the optimal solution? $\endgroup$ – Trenin Nov 4 '14 at 16:09
  • $\begingroup$ @Trenin yes, I'll add some clarification $\endgroup$ – d'alar'cop Nov 4 '14 at 16:12
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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 Jan 23 '15 at 15:33

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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