None of Ponder’s eight families started here. Each belongs to an older kind of puzzle with its own history, and most of them go by several names. If you’ve met one somewhere else, here’s how to recognise it.

We gave the families plain names that describe what you do on the board. The older names are worth knowing, though: your skills carry straight over, and searching for them turns up decades of puzzles and solving advice. Ponder isn’t connected with any of the publishers or apps mentioned below.

Binary: Takuzu, Binairo, Tango

Two symbols, balanced rows and columns, and never three alike in a row. Belgian puzzle makers Peter De Schepper and Frank Coussement published their first Binairo in a Belgian newspaper in the summer of 2009. In Italy, Adolfo Zanellati made the same kind of puzzle under the name Tohu wa Vohu. It’s also sold as Takuzu, Binero and simply “binary puzzle”, usually with 0s and 1s. Many versions add a rule that no two rows or columns can be identical. Ponder’s Binary doesn’t.

LinkedIn’s Tango, launched in October 2024, uses suns and moons and adds marks between neighbours: = for a matching pair, × for a mixed one. That’s the closest relative of Ponder’s Binary, where a double bar means two cells match and a cross means they differ.

Blooms: Star Battle and Queens

One flower in each row, column and region, and no two touching, even at the corners. The genre is Star Battle, created by Hans Eendebak of the Netherlands for the 2003 World Puzzle Championship in Arnhem. Classic Star Battle usually asks for two stars per row, column and region, which makes the no-touching rule bite much harder.

The one-star version reached a lot of people in May 2024 as LinkedIn’s Queens, with crowns instead of stars. Thomas Snyder, who supplied its launch puzzles, describes it as a very accessible one-star Star Battle. Despite the name, it isn’t the chess problem of eight queens: those queens attack along whole rows and diagonals, while here only touching neighbours matter.

Ribbons: Numberlink and Flow

Join each matching pair with a route that doesn’t cross another. The Japanese publisher Nikoli calls this Numberlink, and it ran in their magazine from 1987. The idea is older. Sam Loyd published a version in a newspaper column in 1897, and Henry Dudeney’s 1917 book Amusements in Mathematics includes one called “A Puzzle for Motorists”. Arukone is the same puzzle with letters instead of numbers.

Most people know it from Flow Free, released by Big Duck Games in June 2012, which became the top free iPhone app in the US within weeks. Flow asks you to cover the whole board as well as connect the pairs, and so does Ribbons. That rule is what makes a long detour useful rather than wasteful.

Paths: Zip, Hidato and Numbrix

One route through every cell, visiting the numbers in order. LinkedIn’s Zip, launched in March 2025, has exactly these rules, walls included: start at 1, visit each number in turn, finish on the highest, and never cross yourself or a wall.

Its ancestors ask you to write every number rather than draw a line. In Hidato, invented by the Israeli mathematician Gyora Benedek, the numbers can step diagonally; its name comes from the Hebrew word for riddle. Numbrix, created by Marilyn vos Savant for Parade magazine in 2008, allows only steps up, down and across. Drawing the route instead of numbering it makes the puzzle faster to play on a phone, which is why we chose that form.

Bridges: Hashiwokakero

Nikoli again. Hashiwokakero means “build bridges!” and first appeared in their magazine around 1990. In English it’s usually Hashi or just Bridges, and in parts of Europe it’s sold as Ai-Ki-Ai. The rules have hardly changed since: match each island’s number, at most two bridges between a pair, no crossings, and one connected network.

Light Up: Akari

Nikoli’s Japanese name is Bijutsukan, “art gallery”, which makes sense once you picture the lights as guards who between them have to see every corner of the room. Their English name is Akari, meaning light. It first appeared in their magazine in 2001.

Rectangles: Shikaku

Shikaku ni kire, roughly “divide it into boxes”, is another Nikoli genre from the late 1980s, often shortened to Shikaku. The classic version only gives areas. Ponder’s Rectangles adds shape clues, which say whether a rectangle is square, tall or wide, and round clues that allow any shape. They give smaller boards more to reason about.

Mini Sudoku: Sudoku, or Number Place

The one everybody knows, at a smaller size. Sudoku began in an American puzzle magazine as Number Place, and it was Nikoli that gave it the name Sudoku. “Sudoku” is a Nikoli trademark in Japan, so other Japanese publishers still call it Number Place. Six-by-six versions with boxes three cells wide and two tall are common, and LinkedIn launched its own Mini Sudoku, made with Nikoli, in August 2025.

Why there are so many names

Puzzle genres travel without their names. A newspaper licenses a puzzle and renames it, an app finds a friendlier title, a translator picks a word that sounds right, and a trademark in one country pushes everyone else to invent another. The rules underneath stay remarkably stable, which is good news: if you’re good at one of these under any name, you’re already good at it here.

Every family has a guide with its exact rules in Ponder and a worked example. If you’re coming from one of the puzzles above, check the rules anyway; the differences are small but they matter.

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