First move of bK?

Originally posted by Jusuh
is this trick question?

No.

Originally posted by MikeXx2020
d7

Any analysis to back this up?

Originally posted by BigDoggProblem
This must be a tough one. So far, even Mephisto2 is stumped.n

.... to say the least.
I haven't put much effort in (yet, I hope to find the time) but so far I have trouble to find consistency between different sequences.

What have I found (hopefully correctly) so far:
- white captured 3 pieces with a pawn, nothing else. Means that black's a-pawn must have promoted to get captured as a piece later on. Also the black black-squared bishop has been captured on c3 with the b-pawn, since it is the only black square where white captured on.
- black captured one piece with the d-pawn, must have been the knight (the bishop is wrong colour). Hence the a-pawn captured the black-coloured white bishop (most probably on b2) and then promoted on b1 to a piece, other than a bishop (I use queen at the moment), because it has to be captured on e4 by the white pawn on f3 (yes, it is still possible for me that the capture happened on f3 from g2, and the other black piece was captured on e4, but that makes it more complex even).
- the position of the kings leaves few ways to retro. The knight on e2 must have been there before the king arived (because of the bishop who must have arrived there before too, via e2). And the knight on g2 must have been there before the king arrived as well, because the path to get there would have been via f4 where the white king would have been in check (notice also the rook on g1). I strongly suspect that the white king maneuvered back from h3 to h4-h5-g6-h7 (even further perhaps) to leave room for the black king to go back from f3 to g4-g5-and then to the f-file and ...?
- the bishop on h5 must have arrived there before g6-g7 was played, probably after the kings arrived there, and the h-pawn got to h4. That means that the sequence with the capture on c3 and the promotion by the black pawn occured after that bishop move.
- the moves by the black f- , g- and h-pawn must have been in critical relative sequence to allow the bishop from f8, and the rook from h8 to leave their original position

Originally posted by BigDoggProblem
So far, even Mephisto2 is stumped.

bravo. you did it man!

Originally posted by BigDoggProblem
[fen]8/1p2p3/4p1p1/7b/2p1PpRp/2P1Pk1K/P1PPnPnP/1N1BrRrQ[/fen]
What was the first move made by the black King?

I worked a bit on Mephisto's analysis, but can't get first move of bK, although seems like I'm getting close... Does this clarify something?
"white captured 3 pieces with a pawn, nothing else."
The captures are probably b2xBc3 and g2xf3xe4.

"Means that black's a-pawn must have promoted to get captured as a piece later on." "Hence the a-pawn captured the black-coloured white bishop (most probably on b2) and then promoted on b1 to a piece,other than a bishop"
The capture is then a3xBb2, followed by promotion.

"black captured one piece with the d-pawn, must have been the knight (the bishop is wrong colour)."
d7xNe6 seems good.



We can retract h5 and replace Ng2 by some opposite color piece.f6 must be retracted in the final phase for B,R and K, so we cannot retract c6 and lock the royal family.

-1. Na3-b1 c5-c4
-2. Nc4-a3 f6-f5
-3. Na5-c4 f7-f6
-4. Nb3-a5 c6-c5
-5. Nc1-b3 Nd4-e2
-6. Ne2-c1+ Nb5-d4
-7. Rg5-g4 Na3-b5
-8. Rb5-g5 Nb1-a3


"I strongly suspect that the white king maneuvered back from h3 to h4-h5-g6-h7 (even further perhaps) to leave room for the black king to go back from f3 to g4-g5-and then to the f-file and ...? "

Extracting the wKh3 through probably requires, then, f7-f6, so...

"the moves by the black f- , g- and h-pawn must have been in critical relative sequence."

Originally posted by fetofs
We can retract h5 and replace Ng2 by some opposite color piece.f6 must be retracted in the final phase for B,R and K, so we cannot retract c6 and lock the royal family.

Can you show a diagram of this position? Or retract all the way to it?

EDIT: In the retraction you did show, I think you meant -2...f5-f4 (not f6-f5).

Originally posted by fetofs
According to the retraction (with f5-f4), the position after the moves, (if I didn't do anything wrong):

[fen]8/1p2p3/2p1ppp1/1R5b/4P2p/2P1Pk1K/P1PPNPnP/1n1BrRrQ[/fen]

The g2 knight is likely to be substituted for a white knight.

That wasn't the position that I meant...it was the one further down the road. You had talked about replacing bNg2 with a white piece, so I was curious if you had tried retracting that far yet.

Originally posted by BigDoggProblem
That wasn't the position that I meant...it was the one further down the road. You had talked about replacing bNg2 with a white piece, so I was curious if you had tried retracting that far yet.

I'm trying, not that far yet...

EDIT🙁I see you corrected the position in your reply 😉 I knew I did something wrong! )