Compose a position where

  1. It's White to move
  2. White can deliver checkmate or stalemate in 1 move
  3. Or if they make a different move, then Black can deliver checkmate or stalemate in one 1 move

I needed 6 white pieces and 11 black pieces. Beat me!

Toned down example for understanding:

[FEN "7k/7P/7K/6BP/8/8/8/8 w - - 0 0"]

After the next White move, Black is either mated or stalemated, depending on if White plays Bf6 or not. (This does not meet the 3rd requirement).

  • 2
    Sry but wat does 6w+11b mean?
    – DialFrost
    Apr 9, 2022 at 13:40
  • 1
    6 white pieces and 11 black pieces?
    – Glorfindel
    Apr 9, 2022 at 13:48
  • 1
    How is white getting stalemated or checkmated possible in your above example? Plus, black can't even move if white plays Bf6#. But in your condition, it says Latest after Black's answer it's game over. Apr 9, 2022 at 14:15
  • @AbhyudayVaish: "Toned down example" - with only two possible outcomes. NO example for the wanted position! Apr 10, 2022 at 6:51

2 Answers 2


Just one piece fewer, but how about:

[FEN "5brr/4p1pq/4P1pk/4N1p1/6P1/6PK/6PP/8 w - - 0 1"]

1.Nd7= {Black stalemated} (1.Nf7#) (1.Nxg6 Kxg6#) (1.Nxg6 Qxg6= {White stalemated})
  • 3
    Valid! (1.N~=, 1.Nf7#, 1.Nxg6 Kxg6#, 1.Nxg6 Qxg6=) Apr 10, 2022 at 6:55
  • Accepted for now, although maybe it still can be economized. E.g. consider the far lighter Kh3 Qb4 Pg2 - Kh5 Ph6 Pg6 Pg5 Ph4 Pg3. Almost! (Qg4#, Qa5=, Qxh4 gxh4=, Qa6 g4#, but after Qf4 Black can choose g4+, game over in 1.5 instead of 1. Too bad!) Apr 11, 2022 at 7:31
  • Can an acceptance be withdrawn? This still seems early days for this challenge
    – Laska
    Apr 12, 2022 at 8:19
  • 2
    @Laska The OP can always change their mind about accepted answer
    – Brian Towers
    Apr 13, 2022 at 16:02

I knew it! 13 pieces:

[FEN "8/6p1/6P1/6PB/6P1/4p1pQ/4Pp1p/5K1k w - - 0 0"]

1.Qg2#/1.Qxg3=/1.Qh4 g2#/1.Qxh2+ K,gxh2=

Note that 5 pieces just stand around against 1.Qg4, which also ends the game, but in 1.5 moves - still too bad!

  • Note: If you drop the "any move ends..." condition, it is possible with a mere 5 pieces: yacpdb.org/#407710 Apr 11, 2022 at 10:03
  • I like it! Nice that white has just four options, each of which leads to a different outcome. Apr 11, 2022 at 10:52
  • @DialFrost: BTW, your deleted solution is perfectly legit, if only a bit illegal. :-) Apr 11, 2022 at 17:49

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