Straight sudoku [WSC 2015]
Posted: Sun 17 Feb, 2019 12:42 pm
Potential issue: lack of regions. Here we have only one "full" regions, and a few other renban groups, which can be described as deficit regions. The major part of the grid has no third constraint (i don't consider a single cell as a deficit region).
I chosed the competition puzzle because the example in the instructions booklet was more acceptable in my opinion, with more cells being part of a renban group.