An online trivia questions and answers game with levels from one to fifteen.

Lending library who send wooden puzzles by post according to members' preferences for subject and difficulty. A team of cutters keep adding to the collection using different styles of cut.

Offers a selection of word puzzles, crosswords and sudoku from Chambers Dictionary.

An online collection of puzzles, paradoxes, illusions, nonsense poems, and online puzzle games.

A collection of tricks that can be played on the eye, with physical explanations of how they work.

Provides a collection of games for children as well as ESL students that can be played online.

Offers a daily selection of puzzles including a crossword, sudoko, jigsaw, word puzzler and spot the difference challenge.

Creates and produces a range of puzzles and games for newspapers, magazines and websites; includes a guide to their services and capabilities, with contacts.

Provides a daily sudoku puzzle.

Free online puzzle and riddle game, presented in twelve weekly parts.

Publishes a range of monthly magazines focused on different puzzles, including crosswords, su-doku, wordsearches, and others.

Exhibition gallery of puzzles, holograms and illusions, including an anti-gravity room and the only Ames forced perspective room in the UK. Located in Keswick, Cumbria.

Offers daily sudoku puzzles at all levels, with resources for enthusiasts.

Offers daily puzzles and competitions, crosswords, related puzzles; also provides resources for enthusiasts, and puzzles to download for use in schools.

Daily Telegraph's puzzle site, containing sudoku, crosswords and many other types of puzzle.

A collection of intriguing optical illusions, some classic, some modern.

Member of the World Puzzle Federation. Selects the UK team for the World Sudoku Championship and other international puzzle championships. Includes news, membership information and online contests.

Collection of sudoku and crossword puzzles in various difficulty levels.