(12x15) RnB5 - 1Nrpp3 - kpQRp3 - n1pp2p1 - K3P3 - N2P3p - qPP4P - rb6
How this mate came out?
Solution: 13 a7-a8=R, Nb3-a5; 12 e3-e4, Nd4-b3; 11 e2-e3, Nb5-d4; 10 Nc4-a3, Na3-b5; 9 Ne5-c4, h4-h3; 8 Ng6-e5, h5-h4; 7 Nf8-g6, h6-h5; 6 f7-f8=N, g6-g5; 5 f6-f7, h7-h6! (5-... f7xRe6? becose, in this case, the black Bishop from black squares never will be restored); 4 g5xBf6, Bc3-f6; 3 g4-g5, Bb4-c3; 2 g3-g4, Qc4-a2; 1 Kb3-a4, Qh4-c4; etc...