Find the decisive blow (difficulty 945)

87654321 abcdefgh

White to move

Show solution
87654321 abcdefgh
  1. f4–h5 key move
  2. g6–h5
  3. c1–g5

What makes it

A knight move and a 3-point investment: mate in two. At 945, a warm-up. From a Fischer-random start, with the back rank shuffled, the geometry is anything but routine.