THREE RULES. TWO NUMBERS.
How to play Takuzu
Fill every blank with a 0 or a 1. On Parityvale, zeros are light stones and ones are dark stones. Given clues are fixed; the small dot in their square helps you recognize them.
01
Keep every line balanced.
Every row and every column needs the same number of zeros and ones. That means two of each on a 4×4 grid, three of each on 6×6, and four of each on 8×8.
Two ones are already present in this four-cell row. The final square has to be zero.
02
Never make three together.
No row or column can contain three consecutive zeros or three consecutive ones. Check both directions.
The rule also works across a gap: 0 ? 0 must become 0 1 0. You cannot place a zero in the middle.
03
No duplicate peers.
Every completed row must differ from every other row. Every completed column must differ from every other column.
For example, if one row is 0 0 1 1, another row cannot also be 0 0 1 1. If its partial pattern is 0 ? 1 ?, balance alone allows two arrangements, but uniqueness rules out the duplicate and leaves 0 1 1 0—provided the columns also allow it.
A row is allowed to equal a column. Compare horizontal lines only with horizontal lines, and vertical lines only with vertical lines.
A good place to start.
- Look for a pair of matching numbers. Their next neighbor must be different.
- Look for matching numbers with one gap between them. Fill that gap with the other number.
- Count a nearly complete row or column. If it already has its full allowance of one number, the blanks must be the other.
- Use uniqueness when a completed line would otherwise be repeated. Keep checking the crossing lines.
Every puzzle has one exact solution. Larger grids offer more places to look, so Pocket 4×4 is a comfortable starting point. Classic uses 6×6 and Stretch uses 8×8.
Your controls.
Choose Light, Dark or Erase, then tap a blank square. Tapping a placed number with the same tool clears it. Fixed clues do not change. Conflicting triples, unbalanced lines and duplicate completed lines are highlighted.
Undo reverses a board change. Restart returns to the original clues and can be undone. Reveal a cell corrects a wrong entry first or fills one blank with the value from the unique solution. Reveals remain counted after an undo or restart.
Arrow keys skip fixed clues. Press 0 or 1 to place a number, Delete to erase, and Enter or Space to use the selected tool. With a grid square focused, Ctrl/⌘ + Z undoes.
The daily puzzle changes at midnight UTC. Daily and practice progress save separately in this browser when storage is available. A new practice puzzle replaces the current practice board. If storage is blocked, the current game still works in the open tab.