Meisterwerke

Suppose white can still castle. First white played f6-f7, after that black played g7xf6, and played his bishop to g1/h2, over e3, then white played e2-e3. So the white bishop had to go to e8 via c8 and d7. But then there is no room left to squeeze in all the black pieces and the white rook into the northwest corner. So white may not castle (and the bishop entered the southeast corner over e1,f2). So #1 with 1. Rd1!# (OOO?# illegal).

Solution by Philippe Schnoebelen