Kurt Keller (Germany)
S#11 5+2

The entire position after each half-move, except for the white pawn, shifts down one row at a time during a repeating move pattern (sevenfold echo!). The pattern extends from move 2/6 to move 4/8. Compare the positions reached with 2.Kg2/6.Be3, 2...Kg4(Kh5)/6...Kg3(Kh4), 3.Bf3+/7.Bf2+, ... and finally 4...f6/8...f5.
Keywords: extended switchback (k h3-h4-g4/h5-h4-h3), switchback (k h3-g3-h3), minimal (Black), pawn/corner/model mate.
The animation mode is also available at PDB: https://pdb.dieschwalbe.de/P1408664. (author)