I sacrifice the knight on turn 6 to draw the king out (game engine says it's a blunder, but it's intentional) which forces the king to expose himself. From there I attack with my queen on turn 7, which almost guarantees at least one captured knight, but potentially 2 if they line up just right, as they do here. This game just happened to play just right to lock the black king in a corner for a quick checkmate.