4

It is known what the fastest stalemate is. But what but is the fastest possible stalemate in which castling must be the last move?

33 plies is my best result so far.

[FEN ""]

    

  1. e4 h5 2. Qxh5 d6 3. Qxh8 Bh3 4. Qxg7 Bxg2 5. Qxg8 Bxf1 6. Qxf7+ Kd7 7. Qxf8 Kc6 8. Qxd8 e5 9. Qxd6+ Kb5 10. Qxc7 Bd3 11. Qxb8 Bxc2 12. Qxa8 Bd1 13. Qxa7 Kc4 14. Qxb7 Kd3 15. Nf3 Kc2 16. Qb3+ Kxc1 17. O-O
    2.

Castling for a pin isn’t the only possible motivation though. Here is another 33 plies sequence that shows motivation in protecting pieces and guarding squares.

[FEN ""]

    

  1. f4 e5 2. fxe5 d6 3. exd6 Qg5 4. dxc7 Ke7 5. cxb8=Q Qxg2 6. Qxc8 Qxh2 7. Qxa8 Qxg1 8. Qxa7 g5 9. Qxb7+ Ke6 10. Qxf7+ Ke5 11. Qxf8 Qh2 12. Qxg8 Qh5 13. Qxh8+ Kf4 14. Qxh7 Kg4 15. Bg2 Kg3 16. Qxh5 g4 17. O-O
    2.
Rewan Demontay
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2 Answers2

4

I’ve found a way to reduce the count down to 31 plies.

[FEN ""]

    

  1. f4 e5 2. fxe5 d6 3. exd6 Qg5 dxc7 Qxg2 5. cxb8=Q Qxh2 Qxa7 Qxg1 7. Qxa8 Qg2 8. Bxg2 g5 9. Qxb7 g4 10. Qxc8+ Ke7 11. Qxf8+ Ke6 12. Qxf7+ Ke5 13. Qxg8 Kf4 14. Qxh8 h5 15. Qxh5 Kg3 16. O-O
    2.

White has only two non-capturing moves, the first pawn move and casting. Black uses up all of their moves without rest. Therefore, I think that 31 plies may be optimal unless a pawn capture can be shaved off.

Rewan Demontay
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2

27 piles

[FEN ""]

    

  1. c4 a5 2. h4 h5 3. Qa4 Ra6 4. Qxa5 Rah6 5. Qxc7 f6 6. Qxd7+ Kf7 7. Qxb7 Qd3 8. Qxb8 Qh7 9. Qxc8 Kg6 10. g3 Kf7 11. Bg2 Kg6 12. Nh3 Kf7 13. Qe6+ Kg6 14. O-O 1/2-1/2
    2.
Lucenaposition
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