How to use up an entire airline flight, and then some.
Regular sudoku is pretty easy once you know a handful of rules to narrow down positions. I try to do the medium & hard ones without any pencil marks, but the extra hard I usually use pencil marks on. Still, I seldom take more than 30 minutes to do one.
This thing on the other hand took me hours. You spend a lot of time chasing down dead ends. Not sure I need that kind of aggravation on a regular basis. Maybe I'll just go back to the normal ones.