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EDIT: I think a better name is gg chess, because "gg" (good game) is what folks frequently say at the end of a game.

At major chess events, at the end of a drawn game, the players & arbiter arrange the pieces in the following illegal position, to indicate that the game is over:

[Title "'gg game drawn' game array"]
[FEN "rnbq1bnr/pppppppp/8/4k3/4K3/8/PPPPPPPP/RNBQ1BNR w - - 0 1"]

Now the FIDE movement rules still work in many illegal positions, and this is one of them. White to move is explicitly disallowed from capturing bK (which would in any case be a bad idea because then White could never deliver mate) and so must retreat out of check to d3, e3 or f3. It's now Black to move, with 26 or 27 choices.

Presumably 1. Kf3 is best, because it doesn't block White's central pawns. Black is no longer in check so may now be more aggressive, but alternatively "Petroff's retreat" (1. Kf3 Kf6) may become popular.

Generally this new starting position may address two long-standing gripes: first by reducing draws, and second by giving Black what may be a compensation for playing second.

Can anyone contribute any other opening theory or assessment for this new format, "gg chess"?

BONUS: there is a unique helpmate in 2.5 here! I.e. if the players co-operate, how does White deliver mate on the third move?

MORE: If the position is a White win, the kings go on wKe4, bKd5 and if it's a Black win, the kings are on wKd4, bKe5. (The pattern is that both kings are on the colour of square of the winner.) See this chess.com discussion.

I guess this is so that someone wandering up to a now-empty table can see what the result was. So that's three times the theory!

Does any arbiter have a formal FIDE statement that details this fun policy, please?

AND: In one of these three starting positions, if White plays 1. Kf5?? it's so bad that Black has a forced mate in 7. Can you find it?

[Title "'gg White won' game array"]
[FEN "rnbq1bnr/pppppppp/8/3k4/4K3/8/PPPPPPPP/RNBQ1BNR w - - 0 1"]
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  • 1
    So basically we need engine analysis and evaluation of each of the three positions Kd3/Ke3/Kf3 vs. Ke5. I guess best play will have each side soon hiding their King on g2/g7 or maybe c2/c7 and then it will be some kind of mutant opening theory.
    – Noam D. Elkies
    Aug 22 at 21:09
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    Something looking like a Magnus bongcloud
    – cmgchess
    Aug 23 at 1:41
  • 2
    Actually, there are three game over positions: e4/e5 draw, d4/e5 Black won, e4/d5 White won. So take your new opening theory times three :-)
    – Hauke Reddmann
    Aug 23 at 6:54
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    @NoamD.Elkies: Just did it, Lichess/Stockfish says minimal advantage for White after Kf3 (0.3-0.4 or so), and practically 0.0 elsewise. Depth is standard 22.
    – Hauke Reddmann
    Aug 23 at 7:00
  • When I went deeper (37 or so) I was definitely getting that 1.Kd3 is about -0.3 to 1. ... d5 & 1. ... Kf6
    – Laska
    Aug 23 at 7:37

3 Answers 3

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Solution for the helpmate:

1.Kd3 Kf4 2.e4 e5 3.Nh3#

Nice idea.

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  • 1
    Nice. There's also a unique helpmate in 2.5 in the Kd4/Kd5 version. For the Ke4/Kd5 and Ke4/Ke5 it's not unique; there are even helpmates in 2, but those are not unique either -- indeed for Ke4/Kd5 White's second move is not even needed (1 Kf5 e5 2 ~ d6# or Nh6#).
    – Noam D. Elkies
    Aug 23 at 21:53
  • Yes I was hoping the other two formats would have no helpmates, ha. I don't think Kd4/Kd5 exists as a format, if I've understood Hauke correctly. In the mean time, can you find the White move so bad (in one of the three formats) that Black has a #7? (I've edited the main q)
    – Laska
    Aug 24 at 1:19
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Solution for mate in 7 starting from 1 Kf5?? in the Ke4/Kd5 position:

1 Kf5?? Nh6+ 2 Kf4/i e5+ 3 Ke3/ii Qg5+ 4 Kd3/iii Qg6+/iv 5 Kc3/v Qc6+ 6 Kd3/vi Qc4+ 7 Ke3 Qe4#

Variations:

i) 2 Kg5? e5+ 3 Kh5 g6#.
ii) Kf3/Kg3? Qf6/Qg5+ and a faster mate.
iii) Kf3? Qf4#; f4? Qxf4+ and Qd4#
iv) not e4+? 5 Qc3 Qf6+ 6 d4!
v) or 5 e4+ Qxe4+ 6 Kc3 Qd4+ 7 Kb3 Qb4#
vi) Kb3? Qc4#

P.S. Looks like 1 Kf4?? e5+ mates one move faster, the main line being 2 Ke3 Qg5+ 3 Kd3 Qg6+ 4 Kc3 Qc6+. If instead 2 Kg4 d6+ : wK can't reach the Q-side so Black doesn't need control of b4. Other White options are worse: 2 Kf5?? d6# or Nh6#; 2 Kg3 Qg5+ 3 Kh3 d6+ 4 g4 Qxg4+; and 2 Kf3 Qf6+ 3 Kg3 Qf4+ 4 Kh3+ d6+.

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  • Both of these lines 1.Kf5 #7 & 1.Kf4 #6 are quite clean (when one ignores short solutions) with just one Black branch point in each case, and unique optimal play otherwise. 1.Kf5 Sh6+ 2.Kf4 just adds a prefix move to the 1.Kf4 case. The left-right mirror image is not so simple
    – Laska
    Aug 24 at 15:56
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There should be more than one mate. 1. d4 Kf6 2. Qd2 e6 3. QG5# 1. e3 Kf6 2. Qg4 h6 3. Qf5# Unless White has to move the king on the move 1. hhh

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  • 3
    Hi welcome to chess.stackexchange - in the strange game start position, White is in check. It’s not legal for a player to leave his king in check, so yes White’s first move must be to move the king to a safe square.
    – Laska
    Aug 24 at 4:13

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