(14x14) b6N - 3p3B - 1q1p2p1 - ppk5 - 5b2 - 1PP1p1pP - P1nBP1RP - 2rRrNKQ
White retracts, Black then retracts and helps White mates in 1 (4 solutions).
Solution:
| White and Black retracts | / Helpmates in 1 |
| a) 1 Bg8-h7, c7xNd6 | / 1 c6, Ne4++ |
| b) 1 Nf7-h8, c7xBd6 | / 1 Kc6, Rg3++ |
| c) 1 Rf2-g2, c7xRd6 | / 1 Bd5, Qd5++ |
| d) 1 b2-b3, c7xQd6 | / 1 Kc4, b3++ |
If White retracts Bg8xNh7? or Nf7xNh8? then Black can't retracts c7xNd6 or c7xBd6 becose it's illegal and the problem has no solution. There's no other legal White's retract move.