1. a5-d5 is the only move which ensures White to recycle pieces with his next move. Black won’t play 1. … a5-e5 to defend his piece on c4 (white x), neither can he play 1. … i1-e5 because that would cost him his last GIPF-piece (white 2. f8-f4;xGf3). So, whatever Black’s move will be, White will always have the possibility to play 2. g6;x, although that will enable Black to counter with 2. … f1-f6 and capture 2 of White’s pieces, thus go one more piece ahead.