A King and a Rook may castle everytime and everywhere (even when they have already moved) if:
• both are one the same rank or file
• there are at least two squares between them
• all squares between them are empty
• the King is not in check and he does not move over an observed square.
Castling is done by moving the King two squares towards the Rook and then moving the Rook to the square behind the King.
No. 1682 Andrew Buchanan & James Malcom
Singapore / USA
original - 15.01.2022
Yes the solution is just Staugaard castling! But if we put that as the stipulation, then solving would be trivial. Note that the wR in the starting position is not a tease: it is necessary to prevent duals: Re8-e2# or Qe8-e2#. But it may distract some solvers into thinking *this* is the rook with which wK must dance.1. ... Kc2! is the strongest defence - other responses permit 2. Kd2(+) etc. Beyond that point, Staugaard is the only way. This is C+, and we believe that given the position this implies HC+ for Staugaard, if that were the stipulation.
This composition is intended as an economy record for the Rokagogo/Staugaard excelsior. If someone can produce the same effect with lighter material, we would be very pleased to see it.