@6022
Shortest-proof-game challenge

Well, it appears that I did not in fact have the SPG, since my solution (14.0) is longer than every single length that you have mentioned.
The results I gave at #6024 were for a position that also had a white rook at h1. Did you ever change the position after you first posted it?

For the current #6022, the 13.0 SPG is not unique, nor is any of the 13.5, 14.0, or 14.5 proof games. It has no unique proof game.
Here is one of the SPGs.

The only position I ever posted should have been the version without a rook on h1, since I never created a version with the rook on h1.
Interestingly, I did create several versions with a rook on g1, which were all cooked by Jacobi. But they also had different configurations for black, and I never posted those either.

I hate those positions that must end with white to move as black couldn't have made the last move.
Those are my favorite kind.

I hate those positions that must end with white to move as black couldn't have made the last move.
This might be a fun position for y'all to try out.
My conclusion is that this position does not have any unique proof games. The 11.5 move SPG is not unique, and none of the proof games in 12.0, 12.5, 13.0, or 13.5 is unique.
Would you post what you have as the SUPG for the position?
Well, it appears that I did not in fact have the SPG, since my solution (14.0) is longer than every single length that you have mentioned. I tried to check the position with Jacobi but after 8 hours it still shows up as 0% progress, so I suppose you are the only one who can show us the real SPG.