It has cost me a night sleep, but I have rewritten parts of SudokuGo, my batch generator. It now can generate any Sudoku with boxes of size 2×2, 2×3, 3×3 (duuh), 3×4 and 4×4, including the main variants, Jigsaw, X and DG.

If have also generalized the Windoku concept. A 4×4 sudoku can contain 1 extra 2×2 box in the center, with 3 implied extra groups. No Windows for the irregular formats, but 16×16 can have 9 extra 4×4 boxes, with 7 implied groups. I’m not sure this format will ever work, because the program chokes on generating a valid grid. Too bad if it turns out to be an impossible format, because it looks great. I’ve tested generation of the Windoku groups without box constraints, and that works. The combination may prove to be too much. Just to many conflicting constraints.

Also released SudoCue version 1.5.1. Redid the optimizer as many requested it should work, and also added a menu option to fetch the daily competition puzzle from www.sudoku.org.uk. Undo and redo work on candidates too.

I am now trying to implement Almost Locked Sets. Considering every possibility, the program now found 228 sets in a single grid. Needs some work to filter out the sets that are actually useful. I think I start sorting out the sets that do not overlap, but have a restricted common digit x. It must be possible to find ALS-xz patterns amongst these pairs of sets. I’ll write some more if I made some progress. Would be nice to be the first program that supports ALS, after being the first (and still the only) that supports finned fish.