Originally posted by David113
1.d4 Nc6 2.Kd2 Ne5 3.Ke3 Nf3 4.exf3 Nf6 5.Bc4 Ne4 6.Bd5 Nc5 7.c4 Na6 8.Qa4 Nb8 9.Qc6 dxc6 10.Ne2 Qd6 11.Nec3 Qg3 12.hxg3 Bf5 13.Rh6 Bc2 14.Rf6 Bb3 15.axb3 e6 16.Ra6 Bb4 17.Na4 Bc3 18.bxc3 0-0 19.Ba3 Kh8 20.Bxf8 c5 21.Rd6 Nc6 22.Ne7 Rd8 23.Rc8 Ng8
Black knight goes from g8 to b8 and back.
This problem is an underrated masterpiece; it only got a 1st Honorable Mention in an informal tourney.
The point is that the Ng8 must go hide somewhere so that Black can castle, and, amazingly, b8 is the only possible square
. It's eerie to look at the wide-open board on Black's 4th move and realize that, even with all that time to move the N around, there is no other square to leave him that does not interfere with some other piece's movement later on.
Edit: Hope you solved it instead of digging up the solution from PDB!