Twos

About this game

Twos is the logic puzzle known as Binairo or Takuzu, played here with the paired signs that made the shape a daily habit for so many people. The grid holds two symbols and nothing else — a teal circle and an amber square — and three rules decide where they go. First, you may never have three of the same symbol in a row, across or down. Second, every row and every column must end up with exactly half of each, so on an eight-wide grid that is four circles and four squares in each line. Third, some pairs of neighbouring squares carry a sign between them: an = means the two match, and a × means they differ. A handful of squares arrive filled in and locked, and everything else follows from those three rules. What makes it click is how little you have to hold in your head. There are only two possible answers per square, so a deduction is never a long chain of maybes — it is usually one glance at a pair of neighbours, or a count of what a line has left. That makes it unusually good on a phone and unusually quick to teach: most people are solving properly inside a minute, without reading anything. Every grid here is dealt in the browser and then carved down clue by clue, with the answer re-proved unique after each clue is taken away, so nothing ships that has two answers or that needs a guess. The difficulty labels are earned rather than assigned — each grid is rated by the hardest technique it genuinely forces, which is tested by switching that technique off and seeing whether the grid still falls. Easy grids need only the pair rule and the counting; Medium grids force you to look a step ahead and notice that a symbol would leave a line unable to finish at all; Hard and Expert grids force an assumption you follow until it breaks. Grids run six, eight and ten squares across. A hint reads the board as you have actually left it, names the next square that is forced and explains why — and if you have filled a square that cannot be right, it tells you that instead, rather than helping you further down a dead end. A new grid arrives every day, gentle at the start of the week and expert on Sunday, with a streak to keep, hint-free solves counted separately, and a link that deals a friend the exact grid you just played.

Controls

Tap a square to place a circle, tap it again for a square, and once more to clear it. Squares that arrived filled in are locked and will not change.

Keyboard

• Arrow keys move the cursor around the grid.
• Space or Enter cycles the square under the cursor.
• Z undoes, H asks for a hint, R clears your working.

How to play

Fill every square with one of the two symbols so that all three rules hold at once.

The three rules

• Never three of the same symbol in a row, either across or down. Two side by side is fine; a third is not.
• Every row and every column ends up with exactly half of each symbol.
• A sign between two neighbouring squares must be obeyed: an equals sign means they match, a cross means they differ.

On the board

• The dimmer squares arrived filled in. They are locked, and they are your way in.
• Anything that breaks a rule turns red straight away and the Errors counter rises, so a mistake never waits until the end to show itself.
• Undo and reset are free, and reset clears only your own working — the given squares stay put.
• A hint names the next square that is forced and the reason it is forced.

Read the full Twos rules and strategy →