Soot Mark Blots

A quiet logic puzzle drawn on bone-coloured paper.

Some cells on the sheet carry a number and are never inked. Every other cell is yours to ink or leave bare. Ink that joins edge to edge forms a blot, and here is the whole rule: a number equals the total size of every blot it touches on its four sides. Not the cells beside it. Not the run along a line. The entire blot, however far it sprawls across the sheet.

That one sentence is the whole game, and it hides a trap. Two small blots pressed against a clue count separately. Join them with one careless cell and they become a single blot, so the number the clue is counting jumps. A blot that hugs the same clue on two different sides is still one blot, counted once. A clue of zero wants no ink against it at all. Learning to see those merges before you make them is the skill everything here turns on.

Tap a numbered cell and every blot touching it lights up in its own tint, with a running total against the target underneath. That readout is the teaching tool: watch two tinted chips become one, and watch the arithmetic change with them. A number that is satisfied dims itself out of your way. A number with too much ink against it turns rust red.

Three sheet sizes. 8 x 8 for a short study, 10 x 10 where blots begin to snake between clues, 12 x 12 where an accidental merge is easy to miss. Every board is generated fresh and then proved by a solver before you ever see it, so each puzzle has exactly one answer and can always be reached by reasoning. There is nothing to guess at.

Marking is direct. Tap once to ink a cell, again for a dot you leave as a note to yourself, again to clear it. Drag to lay a whole run in a single stroke. Undo as far back as you like, wipe the sheet clean, or take a hint when a board has you stuck. Finish without hints and your clean run grows.

The ledger keeps count: sheets finished at each size, best times, hint-free finishes, your longest clean streak, total time at the desk, and twelve quiet marks of merit earned only by working.

What this app deliberately does not do:

- No internet. The app holds no network permission at all, so nothing is uploaded and nothing is downloaded, ever.
- No advertising, no analytics, no tracking, no third-party code of any kind.
- No sound whatsoever. Feedback is visual, plus an optional short buzz you can switch off.
- No accounts, no sign-in, no purchases, no currency, no wagering, no chance.
- No countdown pressure. The clock is there if you want it and ignorable if you do not.

Everything runs offline on your device, including the puzzle generator and the uniqueness solver behind it. Progress is stored locally and survives closing the app, and the board you were halfway through is waiting when you come back.

Made for a still moment: a page of ink, a handful of numbers, and one honest answer.