The selected answer to this question shows a game in which all 16 pawns promote to queens so that there is a total of 18 queens on the board. It takes 80 moves...

What is the shortest sequence of moves that achieves this goal?

And just to make things interesting, is the minimum number the same if we ask for 20 rooks, bishops, or knights to be present? This is not obvious, because one of the solutions could require extra moves (for instance, to remove a king from a check given by a new queen).


Solution by Friedrich Burchard & Friedrich Hariuc (1976) in 96 Half-moves

[FEN ""]

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+

Credit goes to d'alar'cop from his answer.

  • 1
    Nice solution. This looks kinda perfect, since the kings only move once and the pieces barely do. – Pablo S. Ocal Nov 5 '14 at 9:03
  • I have not been able to find "proof" that this is the shortest game, but since this solution is almost 40 years old, and nothing else googles up, I'll accept this answer as the closest that I am likely to receive. – yrodro Nov 10 '14 at 15:02
  • 1
    Who wins from this position? – M.M Nov 14 '14 at 3:37
  • Black mates in 1 after either the Queen on f8 or a8 recaptures (forced) and then 1 of 7 possibilities (try finding all of them before looking) 49) ...Qcxd1# ...Qdxd1# ...Qbe4# ...Qhe4# ...Qde4# ...Qdd2# ... Qcd2# Actually, there's an eighth mate if the f8 Queen recaptured. 49)...Qgf2# – Marty Neal Nov 24 '15 at 20:08

Edit: best known is 96 half-moves by Friedrich Burchard & Friedrich Hariuc (1976). (link to answer)

My best score 104 half-moves:

[FEN ""]

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+

Conclusion: it is impossible to make it in 80 half moves as it is required to bring the king to safety and in order to make some pawns swap files, you need to sacrifice minor pieces (at least some of them must not remain in their original squares).

I think it can be improved, but not that much.

Also, yes, the type of promotion affects makes the output differ because queens cover much space and you need to protect the king.

  • (+1) Nice! Especially the d4-d3+ Ke2-f3, nice timing! – Rauan Sagit Mar 16 '14 at 22:16

How about this strategy:

[FEN ""]

1. a4 b5 2. Na3 b4 3. h4 bxa3 4. b4 a5 5. b5 Na6 6. bxa6 Rb8 7. a7 Rb5 8. axb5 c5 9. Rb1 c4 10. Rb3 cxb3 11. Nh3 g5 12. c4 g4 13. c5 gxh3 14. g4 h5 15. g5 Nh6  16. gxh6 Rg8 17. h7 Rg5 18. hxg5 f5 19. Rg1 h2 20. Rg4 fxg4 21. g6 h4 22. c6 Bb7 23. cxb7 g3 24. b6 b2 25. a8=Q a2 26. b8=Q a4 27. b7 a3 28. Qf4 b1=Q 29. b8=Q a1=Q 30. Qbb4 a2 31. Qfc4 e5 32. f4 e4 33. Bg2 h3 34. Bf3 exf3 35. f5 g2 36. d4 Qab2 37. Qdc2 a1=Q 38. Kd2 f2 39. d5 h1=Q 40. d6 f1=Q 41. f6 Be7 42. dxe7 d5 43. g7 Kd7 44. g8=Q d4 45. e4 d3 46. e5 g1=Q 47. f7 Qc6 48. h8=Q h2 49. f8=Q h1=Q 50. e6+ Kc7 51. e8=Q Qbg7 52. Qbb2 Q1g6 53. Qff6 Qhh7 54. Kc3 d2 55. Qgf8 dxc1=Q 56. e7 Q8d7 57. Qef7 Q6h6 58. e8=Q
  • 1
    It would have been brilliant if you could get rid of the bishop and promote the last pawn, just to see queens all over the board :) – Lynob Dec 2 '13 at 22:17
  • @Fischer better now? :) – Rauan Sagit Jan 30 '14 at 11:02
  • yes definitely! – Lynob Jan 30 '14 at 11:44
  • Perhaps you should also explain what you are doing different, since you are not answering the original question. Is it just getting 18 queens and 2 kings and no other pieces on the board or something more? – hkBst Jan 18 at 10:26

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