Answer by
slavetheo (20)
it's called napoleon move. so. for white ones: e2->e4, opponent turn, f1->f4, opp. turn, d1->d3,opp.turn, final move for checkmate : d3->d7. now this system works only if the opponent doesn't make a move for defence. defence could be simply lifting the f7 pawn or horse from g8 to g6