Helpmate in 3
b) Move the black king to c5 in the mating position of a)

(a) 1.Sf5 Se5 2.Rd6 Sf7 3.Bd7 Sd8.
(b) 1.Bb5 Sf7 2.Rc6 Se5 3.Sd6 Sd7.
Humour on the chessboard!

Jacob Hoover: Amazingly, (b) is solved by moving the pieces that moved in part (a) back to their positions in the diagram. So, switchbacks galore!

Richard Stein: This was a fun unwrapping. I would describe this problem as a crab canon, in the style of J.S. Bach, and Douglas Hofstadter after him. "When we walk backwards, we move forwards." -- The Crab, in Hofstadter’s Godel, Escher, and Bach: An Eternal Golden Braid (1979) "Crab Canon".