Takuzu: Binary Logic Puzzle

Binary logic, graded by the technique each board actually needs. Fill a grid with two symbols under three rules: never three of the same symbol in a row, an equal count of each per line, and no two identical rows or columns. Tap a cell to cycle it. That is the whole game. DIFFICULTY THAT MEANS SOMETHING Boards are labelled by the DEEPEST solving technique they genuinely require — Dawn, Day, Dusk and Night — computed by the same deterministic solver that proves each board has exactly one solution. Dawn, Day and Dusk are solvable by pure forward deduction: no hypotheticals, no guessing. Night asks for exactly one bounded "what-if" chain that resolves in a few steps, never open-ended trial and error. We say that precisely rather than promising a "never guess" that a hard board would contradict. WHY YOU'LL STAY • One puzzle a day, byte-identical worldwide, with no server • Streaks, and a fully reconstructible free archive • Several sizes, from a quick grid to a long sit-down • Hints reveal the next forced cell, never the answer MADE TO BE COMFORTABLE • The two symbols always differ in SHAPE, not just colour, at every cell size • A colorblind-safe palette and a fully accessible input path • Play in English, German, Arabic, Persian or Kurdish (Sorani) • Proper right-to-left layout and localized numerals • Fully offline. No account, no sign-up FREE, HONESTLY The daily, the archive, streaks and stats are free with light optional ads. Rewarded video is opt-in and only ever buys a hint. No banner ads on the board, ever. One purchase removes all ads and lifts the hint cap — no subscription.