Shortest-proof-game challenge

Yes. Those are the only single moves that gives minimum number of moves for Black pieces to get positioned. Before Pxf6, this is the only way to maintain Black's progress. After Bxf6, this is the only possible move order for Black, and White always has one unique legal move.

I came across this interesting position and found a 66-move proof game, but I think it can be a fair amount shorter.

Here’s a try I found. It doesn’t quite work because knights can’t lose tempi, neither can the wK shuffling endlessly.

Your game came close. It gave me an idea that let me shorten my 66-move game to 62 moves.

3630

At this rate, in May 2024 you will have it down to 54 moves.

Found it! Longer than the 62.0 move game, but still, that was tricky. I was suspecting the bNe1 was original, but I couldn’t prove that until now.

#3641 in 22.5

part 2 of using the same theme

 #3641 in 22.0 (discovered independently before refreshing the page)

try 3643

#3643 in 25.5

try to shorten it

#3643 in 23.5, only improvement is if castling is possible

castling which side?

i was thinking 0-0 but that increases one move (kf1 kg2 kh3 and rf1 become 0-0,kg2,kg3 but knights lose two moves)

wait, do you mean 0-0-0?

i was talking about black castling