(14x13) n5b1 - p1ppp1RP - 1N1N1kp1 - PrP5 - 5P2 - 1Kp1RQ1B - 1b1P2P1 - qrB5
Each band, Black and White, retracts 5 moves, then White mates in 1.
Solution:
Black and White retracts 5 b4xc3ep, c2-c4; 4 
e6xf6,
e5xf6ep; 3 f7-f5, 
f5-d6; 2 f6-e6, e4-e5;
1 e6-f6, d5-b6.
Now White mates with 1 d4++