Clubs, championships and communities for puzzle lovers
Is there a club for this kind of sudoku? Not one just for Number Islands yet, but a lively world of variant-sudoku fans is waiting.
There isn't (yet!) a club devoted only to Number Islands. But puzzles with hidden regions belong to a well-loved family of variant sudoku, and the people who solve them have built friendly communities, online contests and even world championships. Here's where to find them.
Know what to search for
The genre closest to Number Islands is usually called Chaos Construction: sudoku where you must work out the regions yourself. Related styles are jigsaw or irregular sudoku (regions are given, but oddly shaped) and the wider world of variant sudoku. Using these names will help you find puzzles and fellow fans.
Communities and puzzle sites
- Logic Masters Deutschland (logic-masters.de). A German puzzle association whose puzzle portal hosts a huge collection of user-made puzzles, including many Chaos Construction sudokus. The site has an English option, and it organises German championships, including the German Sudoku Championship.
- Logic Masters India (logicmastersindia.com). Runs regular online puzzle and sudoku tests that anyone can enter from home.
- GM Puzzles (gmpuzzles.com). A long-running blog of hand-made puzzles, with a big archive of sudoku variations.
- Cracking the Cryptic (YouTube). A hugely popular channel where two expert solvers work through variant sudokus out loud. It's a great way to learn new techniques.
- Reddit: r/sudoku and r/puzzles are good places to ask questions, share solves and find recommendations.
Championships
- World Puzzle Federation (worldpuzzle.org). The international body behind the World Sudoku Championship and the World Puzzle Championship, where national teams compete. It also runs the online Sudoku Grand Prix series, where variant sudokus are standard fare.
- UK Puzzle Association (ukpuzzles.org). A volunteer-run non-profit that holds the UK Sudoku and Puzzle Championships online and selects the UK's world-championship teams.
- Many other countries have national puzzle associations that select teams for the world championships. Germany and India are two of the most active. Check the WPF site for your country.
Start your own island club
Local clubs often begin with a handful of friends and a stack of printouts. Our printables make it easy:
- Pick a regular time, such as a lunch break, a library afternoon or a family night.
- Print the same puzzle for everyone from the Printables page.
- Race for the target time printed on each sheet, or solve in pairs and compare reasoning.
- Work up through the island groups together, from The Shallows to The Far Storms.
Running a puzzle club at a school or library? We'd love to hear about it at support@numberislands.com.
Links go to independent organisations not affiliated with Number Islands. Details such as contest schedules change, so check each site for current information.
