Interesting! It looks like the game never requires you to backtrack, there's always a way forward by applying some rule exactly once. I guess that's why you hav

Interesting! It looks like the game never requires you to backtrack, there's always a way forward by applying some rule exactly once. I guess that's why you have the requirement for unique rows and columns (which is pretty jarring gameplay wise), otherwise the forced games would be much more boring. That kinda limits the possible intellectual enjoyment from the game, though. Without the requirement for unique rows and columns, the game would become Simon Tatham's "Unruly" (http://www.chiark.greenend.org.uk/~sgtatham/puzzles/js/unruly.html http://www.chiark.greenend.org.uk/~sgtatham/puzzles/js/unrul...), which is extremely fun because you need to think ahead :-)