No.1597 (ND&VC)

(C+ Jacobi using the constraints 000 (Authors))

Theme
Both sides apparently castled short, although both sides castled long in the game.
Context
The proof game is actually the answer to challenge no 56 from the compilation of some fascinating open problems in the Proof Game genre.
Nicolas Dupont and Marek Kolčák have already shown this difficult theme in an orthodox proof game with apparent long castlings and real short castlings (see 17849 from Die Schwalbe 297/2019).
More about the genesis of that proof game can be found in a post from Thomas Brand's blog. As you will read in the comments, it was quite a very heated debate!
The present proof game is actually the first rendering of this difficult challenge using a particularly suitable fairy condition.