the new route passes closer to a blocked tile
This metric might be important when traveling with bigger party, but I would not pay too much attention to it.
It basically shows how much close to the wall the path happens to be.
With diagonal neighbours enabled, this opens possibility to have more of the close-to-corner paths.
Tighter paths: 333 out of 4663 requests passed closer to walls, showing only 24 exemplary illustrations.
