Prolonged BB-Rundlauf: h3-g2-e4-f5-h3 and g2-e4-f5-h3-g2. The first black move and mating move are the same move.
Annihilation of WPe4, Umnov effect, anti-critical play, multiple gate-opening effect, Kniest theme, 3 active self-blocks, BK<->BB obstruction in the position before mate. Economical mate in the center of chessboard after zugzwang. (Author)