You can complete 3Doku completely manually, but it can get annoying, so here are some tools to make it a bit easier.

Autopencil will delete pencilmarks when you add a number with the pen tool. It is convenient, but be careful as if you make a mistake, Autopencil might delete a number which is correct.

Neither "fill in pencil marks" and "autopencil" count as a hint or affect your streak.

This will flag up incorrect guesses in yellow (when the pen tool is selected). This is very useful but can be high stakes — if any mistakes get highlighted, that counts as taking a hint, and your streak will be reset.

3Doku is a classic sudoku wrapped around a cube, although unlike a classic sudoku it uses the numbers 1-16 rather than 1-9.

Each face of the solved cube contains each of the numbers 1-16, and like a classic sudoku there are also "rows" and "columns" which contain the numbers 1-16.

Look at the rows and columns within each face, and follow them over the edge onto the next face, wrapping all the way around the cube until you get back to the first face. If you need help with this, select the 'highlighter' tool, in 'groups for cell' mode, and click a cell on the cube — the groups its in will be highlighted.

The puzzles are easy on Mondays, and get progressively harder until Saturday. Sunday puzzles are a wildcard, but are never too easy. You probably shouldn't expect a Wordle-style 200-day streak here, so feel free to use the hint system, especially while learning. Also, the automatic pencilmarks in the assistance panel make playing much less annoying and doesn't count as a hint so your streak will stay intact.

You should also check out my word-based puzzle, Cell Tower!

3Doku © 2023 @Andrew_Taylor. Font is Montserrat. Icons are from FontAwesome Free.

The controls are navigated like any other webpage, using tab, the arrow keys, and space. There are a couple of extra controls attached to the cube itself, though.

Rather than tabbing through the 96 textboxes that make up the cube, the cube acts as a single tab stop and you move between cells using the arrow keys. This can get a little confusing when you go round a corner — where two faces meet, they aren't always the same way up, so you can get two cells that are both "above" each other, and pressing "up" will just skip between them. As an alternative, you can move in a more consisitent, if less obvious, direction by using R and F to track around the red bands, T and G to track around the green bands, and Y and H to track around the yellow bands. This works even when those bands are not highlighted, although obviously it's tricky to use properly then.

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