H. G. Muller wrote on Thu, Mar 26, 2020 12:01 PM UTC:
Indeed, if there is a diagonal path from Joker to King, Bishops and Queens would be pinned.
If there is a diagonal path of a black Joker to f1 (say from d3), I would not think that this would forbid O-O, because it also doesn't forbid Kf1,
The tricky question is what to do when the Joker has a diagonal path do e1 (say from c3). Can white castle now, or is he in check, and consequently cannot? This again depends on how one imagines the Joker to move after a turn pass. And if he keeps his old move in that case, it depends on the previously moved piece.
Indeed, if there is a diagonal path from Joker to King, Bishops and Queens would be pinned.
If there is a diagonal path of a black Joker to f1 (say from d3), I would not think that this would forbid O-O, because it also doesn't forbid Kf1,
The tricky question is what to do when the Joker has a diagonal path do e1 (say from c3). Can white castle now, or is he in check, and consequently cannot? This again depends on how one imagines the Joker to move after a turn pass. And if he keeps his old move in that case, it depends on the previously moved piece.