Series-helpmate in 8

The task is for Black to play eight consecutive moves, culminating in a position where White can deliver mate in one. Clearly, that final blow must be d2–d3 — and for it to land, the black king must stand on c4, with every neighbouring flight square smothered by its own men.

The final configuration of the black units isn’t hard to visualise: king on c4; pawns on c5 and d4; queen on b4; rooks on b3 and b5; and bishops on c3 and d5. Only one eight-move sequence can achieve this: 1.Kc4 2.Qb4 3.Rb3 4.Bc3 5.d4 6.Rb5 7.c5 8.Bd5 — enabling White to finish with d3#.