PG in 15.0 moves

Originally posted by THUDandBLUNDER
Yes, I am aware that Qh4 is a potential check.

Yes, of course, and that explains why there is no choice on white's 9th move completion (no rook).

Solution:
1.a4 d5 2.Ra3 Bh3 3.Rb3 Kd7 4.Rb6 axb6 5.f4
White has all the free time. He has to promote the pawn just to allow black to take it.
5...Rxa4 6.f5 Re4 7.f6 Re6 8.fxe7 f5 9.e8=N!
The removal of the f-pawn has created a problem: Black's Qh4 gives check. The swiftest way to deal with that check is to use a promoted N to shield.
9...Bc5 10.Nd6 Bd4 11.Ne4 Qh4+ 12.Ng3 Qe4
Having done its job, the wN must disappear from the board. The only possible square is e8, the square on which it was promoted.
13.Nh5 g5 14.Ng7 Nf6 15.Ne8 Rhxe8
The promoted wN leaves the promotion square and returns to it via a circular route (rundlauf), and is paradoxically captured at the end.

Michel Caillaud
1st Prize, GD50-JT

PG in 15.0

A nice puzzle, BigDogg.