Another possibility?
Mirror mate puzzles

This is the only one I could think of with most adjoining spaces surrounding King for a mate. Question is what is the fewest pieces possible for most adjacent squares vacant with mate?

Well it's not really a mirror mate Ronald, as the adjoining 8 squares around the King are not empty!

This is the only one I could think of with most adjoining spaces surrounding King for a mate. Question is what is the fewest pieces possible for most adjacent squares vacant with mate?
It's not clear what you mean by 'most adjoining spaces'. Is it something like 'largest rectanglur area of squares with only a bK in it'?

This is the only one I could think of with most adjoining spaces surrounding King for a mate. Question is what is the fewest pieces possible for most adjacent squares vacant with mate?
It's not clear what you mean by 'most adjoining spaces'. Is it something like 'largest rectanglur area of squares with only a bK in it'?
Yup! Per definition of Oxford Companion that is it! I believe it has something to do with squares forming an "invisible wall of mirrors" around the king to completely immobilize him.
Mirror, mirror, on the wall....
This thread is for all mirror mate puzzles.
Mirror mate is where a mate occurs with eight adjoining squares of a king is unoccupied (from The Oxford Companion to Chess).
Here is a continuation of Browne-Quinterors at Wijk aan Zee in 1974. Sicilian Defence, Moscow Variation.