Find the decisive blow (difficulty 915)

87654321 abcdefgh

White to move

Show solution
87654321 abcdefgh
  1. d5–c6 key move
  2. d4–e3
  3. b5–b7

What makes it

A bishop move and a 2-point investment: mate in two. At 915, an approachable find. From a Fischer-random start, with the back rank shuffled, the geometry is anything but routine.