These puzzles have been posted by MikeJapan and h3lix on DJ-Ape’s forum.

They are an interesting variation which combine a zero-killer with crosswords in the empty regions. I adapted SumoCue to handle these puzzles. In “letter” mode, the program shows the placed digits and candidates as letters in the “zero” regions. In stead of cage combinations, there is a new tool that shows all remaining valid words for each region. This tool can be set to “horizontal” and “vertical” mode, because a single cell can belong to 2 words.

I have already implemented a new solving technique that eliminates candidates that do not occur in any valid word. There is a background interface with the Internet Anagram Server at Wordsmith to retrieve all valid words for the given letters. The SumoCue V2 save format can save the letter table.

I’m not sure what techniques to implement next. It’s easy to build the word lists into DLX and verify a unique solution, but it is nicer to have more human executable solving techniques. The next target could be invalid word combinations, where the combination violates the sudoku rule by placing repeating digits in a box. This could lead to words being eliminated from the list, because they cannot be used in any combination, which in turn could cause letter eliminations.

It looks like a pretty far-fetched technique, but it is still logical.

Another technique that I’ve been thinking about is a variation on the killer pair/triple/quad. When a word, when placed, would eliminate all candidates from a cell, or all combinations from a cage, the word cannot be placed. All cells of the cage must “see” the word, so this is not a technique that can be used on a large scale.

I’ll see what comes next.