Ernest Clement Mortimer Shortest Proof Games, 1991 Version by A. Frolkin
15+13. Position after Black's 4th move. How did the game go?
Solution: White must capture three black men in four moves. With his missing knight. The only game is 1. Nf3 e5 2. Nxe5 Ne7 3. Nxd7 Nec6 4. Nxb8 Nxb8. Paradoxically the bN now on b8 really is the bKN from g8 !