By Nick
You fill a grid with two kinds of thing. No three alike in a row. Each line split half and half. If that sounds familiar, you may know it as Tango, Takuzu, Binairo or just a binary puzzle. It's the same idea under each name, with a few small changes from one version to the next.
This post sorts out the names, shows what each version adds or drops, and tells you where to play one for free.
The rules they all share
Every version of this puzzle uses a square grid and two symbols. It might be 0 and 1, two colours, suns and moons, or cats and dogs. Two rules are always there:
- No three in a row. Three of the same symbol can't sit next to each other, across or down.
- Balance. Every row and every column holds the same number of each symbol. On a 6×6 board, that's three and three.
Each puzzle starts with some squares filled in and has one answer. Those two rules alone give you most of the moves you'll ever use. Two alike force the squares on each side. A gap between two alike must hold the other symbol. A line that has its half of one symbol fills the rest with the other.
Binairo
Binairo was published by two Belgian puzzle makers, Peter De Schepper and Frank Coussement. It uses 0s and 1s. You'll find it in puzzle books, newspapers and apps, often in bigger sizes than you'd meet in a daily phone game.
Takuzu
Takuzu is the name some other publishers use for the same puzzle. The rules match Binairo's. If you're searching for "Takuzu rules" or "Binairo online", you're looking for the same game.
Classic Takuzu and Binairo usually add a third rule: no two rows can be the same, and no two columns can be the same. On a hard board, this rule can be the only way forward. If two rows are nearly full and match so far, the last squares must make them different.
Binary puzzle, 0h h1 and Unruly
"Binary puzzle" is the plain-English name, and it's what many puzzle sites call it. A few versions have their own names. 0h h1 is a free version with red and blue tiles. Simon Tatham's free puzzle collection has one called Unruly, with black and white squares. Each changes the look, but the core of the puzzle stays the same.
Tango
Tango is LinkedIn's daily version, played with suns and moons on a 6×6 grid. It keeps the two shared rules and makes two changes.
First, it adds signs on the edges between some squares. An = means the two squares hold the same symbol. A × means they hold different ones. The signs do much of the work that extra starting squares would do in Takuzu, so a Tango board can start with only a few symbols in place.
Second, Tango doesn't state the unique-rows rule. You solve it with the two shared rules and the signs. Our LinkedIn Tango guide covers its rules in full.
Cats & Dogs
Cats & Dogs is our version, and it plays by the same rules as Tango. A 6×6 grid. Cats and dogs instead of suns and moons. No three alike in a row, three of each in every line, and = and × signs between some squares.
Like Tango, we don't use the unique-rows rule. You'll never need it to solve one of our boards. Each one has exactly one answer under the three rules, and you can reach it by logic with no guessing.
How the versions compare
- Symbols: 0 and 1 (Binairo, Takuzu), coloured tiles or squares (0h h1, Unruly), suns and moons (Tango), cats and dogs (ours). The symbol never changes the logic.
- Unique rows and columns: usually yes in classic Takuzu and Binairo. No in Tango and Cats & Dogs.
- = and × signs: Tango and Cats & Dogs. Most classic versions don't have them.
- Board size: Tango and Cats & Dogs are 6×6. Puzzle books and apps for the classic versions often go much bigger, such as 10×10, 12×12 or larger. Most versions use even sizes, so every line can split evenly.
If you can solve one, you can solve them all. The moves carry over, and our Tango strategy guide shows each one on a board. The only new skills are reading the signs, if you come from Takuzu, or watching for matching rows, if you come from Tango.
Where to play free
LinkedIn gives you one Tango a day. If you want more, Cats & Dogs has three new boards every day, Easy, Medium and Hard. It runs in your browser with no app and no account. Endless mode deals a new board whenever you finish one, and the archive keeps every board we've published. We're not affiliated with LinkedIn, and we don't publish their answers. These are our own boards.
To read more about how our version works, see Meet Cats & Dogs. To get faster, try the seven most common Tango mistakes and how to fix them. To play the classic version, see Takuzu and Binairo online.