3. Aug, 2022
Retros
In chess problems, retrograde analysis is a technique employed to determine which moves were played leading up to a given position. While this technique is rarely needed for solving ordinary chess problems, there is a whole subgenre of chess problems in which it is an important part; such problems are known as retros... Wikipedia
Retrograde analysis sounds daunting, but is a very enjoyable form of recreational chess, requiring humour and lateral thinking... ChessBase
Diagram: White to move - "As you see, Watson, neither side is mated—nor even in check. And we are given that your side is White. The question now is this: Given that Black moved last, what was his last move, and White's last move?" - The Chess Mysteries of Sherlock Holmes